diff --git a/langchain/src/document_loaders/fs/unstructured.ts b/langchain/src/document_loaders/fs/unstructured.ts
index edb60008aca1..e3b62a9cfbc3 100644
--- a/langchain/src/document_loaders/fs/unstructured.ts
+++ b/langchain/src/document_loaders/fs/unstructured.ts
@@ -126,6 +126,11 @@ type UnstructuredDirectoryLoaderOptions = UnstructuredLoaderOptions & {
   unknown?: UnknownHandling;
 };
 
+type UnstructuredMemoryLoaderOptions = {
+  buffer: Buffer;
+  fileName: string;
+};
+
 /**
  * @deprecated - Import from "@langchain/community/document_loaders/fs/unstructured" instead. This entrypoint will be removed in 0.3.0.
  *
@@ -139,6 +144,10 @@ type UnstructuredDirectoryLoaderOptions = UnstructuredLoaderOptions & {
 export class UnstructuredLoader extends BaseDocumentLoader {
   public filePath: string;
 
+  private buffer?: Buffer;
+
+  private fileName?: string;
+
   private apiUrl = "https://api.unstructured.io/general/v0/general";
 
   private apiKey?: string;
@@ -175,7 +184,9 @@ export class UnstructuredLoader extends BaseDocumentLoader {
   private maxCharacters?: number;
 
   constructor(
-    filePathOrLegacyApiUrl: string,
+    filePathOrLegacyApiUrlOrMemoryBuffer:
+      | string
+      | UnstructuredMemoryLoaderOptions,
     optionsOrLegacyFilePath: UnstructuredLoaderOptions | string = {}
   ) {
     super();
@@ -183,11 +194,20 @@ export class UnstructuredLoader extends BaseDocumentLoader {
     // Temporary shim to avoid breaking existing users
     // Remove when API keys are enforced by Unstructured and existing code will break anyway
     const isLegacySyntax = typeof optionsOrLegacyFilePath === "string";
-    if (isLegacySyntax) {
+    const isMemorySyntax =
+      typeof filePathOrLegacyApiUrlOrMemoryBuffer === "object";
+
+    if (isMemorySyntax) {
+      this.buffer = filePathOrLegacyApiUrlOrMemoryBuffer.buffer;
+      this.fileName = filePathOrLegacyApiUrlOrMemoryBuffer.fileName;
+    } else if (isLegacySyntax) {
       this.filePath = optionsOrLegacyFilePath;
-      this.apiUrl = filePathOrLegacyApiUrl;
+      this.apiUrl = filePathOrLegacyApiUrlOrMemoryBuffer;
     } else {
-      this.filePath = filePathOrLegacyApiUrl;
+      this.filePath = filePathOrLegacyApiUrlOrMemoryBuffer;
+    }
+
+    if (!isLegacySyntax) {
       const options = optionsOrLegacyFilePath;
       this.apiKey = options.apiKey;
       this.apiUrl = options.apiUrl ?? this.apiUrl;
@@ -209,14 +229,20 @@ export class UnstructuredLoader extends BaseDocumentLoader {
   }
 
   async _partition() {
-    const { readFile, basename } = await this.imports();
+    let { buffer } = this;
+    let { fileName } = this;
+
+    if (!buffer) {
+      const { readFile, basename } = await this.imports();
 
-    const buffer = await readFile(this.filePath);
-    const fileName = basename(this.filePath);
+      buffer = await readFile(this.filePath);
+      fileName = basename(this.filePath);
+
+      // I'm aware this reads the file into memory first, but we have lots of work
+      // to do on then consuming Documents in a streaming fashion anyway, so not
+      // worried about this for now.
+    }
 
-    // I'm aware this reads the file into memory first, but we have lots of work
-    // to do on then consuming Documents in a streaming fashion anyway, so not
-    // worried about this for now.
     const formData = new FormData();
     formData.append("files", new Blob([buffer]), fileName);
     formData.append("strategy", this.strategy);
diff --git a/langchain/src/document_loaders/tests/unstructured.int.test.ts b/langchain/src/document_loaders/tests/unstructured.int.test.ts
index e30913e10a2d..b0b0712118a6 100644
--- a/langchain/src/document_loaders/tests/unstructured.int.test.ts
+++ b/langchain/src/document_loaders/tests/unstructured.int.test.ts
@@ -3,6 +3,7 @@
 
 import * as url from "node:url";
 import * as path from "node:path";
+import { readFile } from "node:fs/promises";
 import { test, expect } from "@jest/globals";
 import {
   UnstructuredDirectoryLoader,
@@ -29,6 +30,34 @@ test.skip("Test Unstructured base loader", async () => {
   }
 });
 
+test.skip("Test Unstructured base loader with buffer", async () => {
+  const filePath = path.resolve(
+    path.dirname(url.fileURLToPath(import.meta.url)),
+    "./example_data/example.txt"
+  );
+
+  const options = {
+    apiKey: process.env.UNSTRUCTURED_API_KEY!,
+  };
+
+  const buffer = await readFile(filePath);
+  const fileName = "example.txt";
+
+  const loader = new UnstructuredLoader(
+    {
+      buffer,
+      fileName,
+    },
+    options
+  );
+  const docs = await loader.load();
+
+  expect(docs.length).toBe(3);
+  for (const doc of docs) {
+    expect(typeof doc.pageContent).toBe("string");
+  }
+});
+
 test.skip("Test Unstructured base loader with fast strategy", async () => {
   const filePath = path.resolve(
     path.dirname(url.fileURLToPath(import.meta.url)),
diff --git a/libs/langchain-community/src/document_loaders/fs/unstructured.ts b/libs/langchain-community/src/document_loaders/fs/unstructured.ts
index f9040b11110a..d069d306c33d 100644
--- a/libs/langchain-community/src/document_loaders/fs/unstructured.ts
+++ b/libs/langchain-community/src/document_loaders/fs/unstructured.ts
@@ -120,6 +120,11 @@ type UnstructuredDirectoryLoaderOptions = UnstructuredLoaderOptions & {
   unknown?: UnknownHandling;
 };
 
+type UnstructuredMemoryLoaderOptions = {
+  buffer: Buffer;
+  fileName: string;
+};
+
 /**
  * A document loader that uses the Unstructured API to load unstructured
  * documents. It supports both the new syntax with options object and the
@@ -131,6 +136,10 @@ type UnstructuredDirectoryLoaderOptions = UnstructuredLoaderOptions & {
 export class UnstructuredLoader extends BaseDocumentLoader {
   public filePath: string;
 
+  private buffer?: Buffer;
+
+  private fileName?: string;
+
   private apiUrl = "https://api.unstructured.io/general/v0/general";
 
   private apiKey?: string;
@@ -167,7 +176,9 @@ export class UnstructuredLoader extends BaseDocumentLoader {
   private maxCharacters?: number;
 
   constructor(
-    filePathOrLegacyApiUrl: string,
+    filePathOrLegacyApiUrlOrMemoryBuffer:
+      | string
+      | UnstructuredMemoryLoaderOptions,
     optionsOrLegacyFilePath: UnstructuredLoaderOptions | string = {}
   ) {
     super();
@@ -175,11 +186,20 @@ export class UnstructuredLoader extends BaseDocumentLoader {
     // Temporary shim to avoid breaking existing users
     // Remove when API keys are enforced by Unstructured and existing code will break anyway
     const isLegacySyntax = typeof optionsOrLegacyFilePath === "string";
-    if (isLegacySyntax) {
+    const isMemorySyntax =
+      typeof filePathOrLegacyApiUrlOrMemoryBuffer === "object";
+
+    if (isMemorySyntax) {
+      this.buffer = filePathOrLegacyApiUrlOrMemoryBuffer.buffer;
+      this.fileName = filePathOrLegacyApiUrlOrMemoryBuffer.fileName;
+    } else if (isLegacySyntax) {
       this.filePath = optionsOrLegacyFilePath;
-      this.apiUrl = filePathOrLegacyApiUrl;
+      this.apiUrl = filePathOrLegacyApiUrlOrMemoryBuffer;
     } else {
-      this.filePath = filePathOrLegacyApiUrl;
+      this.filePath = filePathOrLegacyApiUrlOrMemoryBuffer;
+    }
+
+    if (!isLegacySyntax) {
       const options = optionsOrLegacyFilePath;
       this.apiKey =
         options.apiKey ?? getEnvironmentVariable("UNSTRUCTURED_API_KEY");
@@ -205,14 +225,20 @@ export class UnstructuredLoader extends BaseDocumentLoader {
   }
 
   async _partition() {
-    const { readFile, basename } = await this.imports();
+    let buffer = this.buffer;
+    let fileName = this.fileName;
+
+    if (!buffer) {
+      const { readFile, basename } = await this.imports();
 
-    const buffer = await readFile(this.filePath);
-    const fileName = basename(this.filePath);
+      buffer = await readFile(this.filePath);
+      fileName = basename(this.filePath);
+
+      // I'm aware this reads the file into memory first, but we have lots of work
+      // to do on then consuming Documents in a streaming fashion anyway, so not
+      // worried about this for now.
+    }
 
-    // I'm aware this reads the file into memory first, but we have lots of work
-    // to do on then consuming Documents in a streaming fashion anyway, so not
-    // worried about this for now.
     const formData = new FormData();
     formData.append("files", new Blob([buffer]), fileName);
     formData.append("strategy", this.strategy);
diff --git a/libs/langchain-community/src/document_loaders/tests/unstructured.int.test.ts b/libs/langchain-community/src/document_loaders/tests/unstructured.int.test.ts
index e30913e10a2d..b0b0712118a6 100644
--- a/libs/langchain-community/src/document_loaders/tests/unstructured.int.test.ts
+++ b/libs/langchain-community/src/document_loaders/tests/unstructured.int.test.ts
@@ -3,6 +3,7 @@
 
 import * as url from "node:url";
 import * as path from "node:path";
+import { readFile } from "node:fs/promises";
 import { test, expect } from "@jest/globals";
 import {
   UnstructuredDirectoryLoader,
@@ -29,6 +30,34 @@ test.skip("Test Unstructured base loader", async () => {
   }
 });
 
+test.skip("Test Unstructured base loader with buffer", async () => {
+  const filePath = path.resolve(
+    path.dirname(url.fileURLToPath(import.meta.url)),
+    "./example_data/example.txt"
+  );
+
+  const options = {
+    apiKey: process.env.UNSTRUCTURED_API_KEY!,
+  };
+
+  const buffer = await readFile(filePath);
+  const fileName = "example.txt";
+
+  const loader = new UnstructuredLoader(
+    {
+      buffer,
+      fileName,
+    },
+    options
+  );
+  const docs = await loader.load();
+
+  expect(docs.length).toBe(3);
+  for (const doc of docs) {
+    expect(typeof doc.pageContent).toBe("string");
+  }
+});
+
 test.skip("Test Unstructured base loader with fast strategy", async () => {
   const filePath = path.resolve(
     path.dirname(url.fileURLToPath(import.meta.url)),