diff --git a/.changeset/unlucky-numbers-cheer.md b/.changeset/unlucky-numbers-cheer.md
new file mode 100644
index 0000000000..8c320d6686
--- /dev/null
+++ b/.changeset/unlucky-numbers-cheer.md
@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Added `cause` in `HttpRequestError`.
diff --git a/src/errors/base.ts b/src/errors/base.ts
index 5170893220..2c6c815812 100644
--- a/src/errors/base.ts
+++ b/src/errors/base.ts
@@ -1,20 +1,13 @@
 import { getVersion } from './utils.js'
 
 type BaseErrorParameters = {
+  cause?: BaseError | Error | undefined
+  details?: string | undefined
   docsBaseUrl?: string | undefined
   docsPath?: string | undefined
   docsSlug?: string | undefined
   metaMessages?: string[] | undefined
-} & (
-  | {
-      cause?: undefined
-      details?: string | undefined
-    }
-  | {
-      cause: BaseError | Error | undefined
-      details?: undefined
-    }
-)
+}
 
 export type BaseErrorType = BaseError & { name: 'ViemError' }
 export class BaseError extends Error {
diff --git a/src/errors/request.ts b/src/errors/request.ts
index a824ff0af6..c9ec1cfbeb 100644
--- a/src/errors/request.ts
+++ b/src/errors/request.ts
@@ -16,18 +16,21 @@ export class HttpRequestError extends BaseError {
 
   constructor({
     body,
+    cause,
     details,
     headers,
     status,
     url,
   }: {
     body?: { [x: string]: unknown } | { [y: string]: unknown }[] | undefined
+    cause?: Error | undefined
     details?: string | undefined
     headers?: Headers | undefined
     status?: number | undefined
     url: string
   }) {
     super('HTTP request failed.', {
+      cause,
       details,
       metaMessages: [
         status && `Status: ${status}`,
diff --git a/src/utils/rpc/http.test.ts b/src/utils/rpc/http.test.ts
index bbb26996d0..dab97d2519 100644
--- a/src/utils/rpc/http.test.ts
+++ b/src/utils/rpc/http.test.ts
@@ -303,6 +303,27 @@ describe('request', () => {
     )
   })
 
+  test('fetch error', async () => {
+    vi.stubGlobal('fetch', () => {
+      throw new Error('foo', { cause: new Error('bar') })
+    })
+
+    const client = getHttpRpcClient(anvilMainnet.rpcUrl.http)
+
+    try {
+      await client.request({
+        body: {
+          method: 'eth_getBlockByNumber',
+          params: [numberToHex(anvilMainnet.forkBlockNumber), false],
+        },
+      })
+    } catch (error) {
+      expect((error as Error).cause).toMatchInlineSnapshot('[Error: foo]')
+    }
+
+    vi.unstubAllGlobals()
+  })
+
   // TODO: This is flaky.
   test.skip('timeout', async () => {
     const client = getHttpRpcClient(anvilMainnet.rpcUrl.http)
@@ -371,12 +392,12 @@ describe('http (batch)', () => {
     ).toMatchInlineSnapshot(`
       [
         {
-          "id": 89,
+          "id": 91,
           "jsonrpc": "2.0",
           "result": "anvil/v0.2.0",
         },
         {
-          "id": 90,
+          "id": 92,
           "jsonrpc": "2.0",
           "result": "anvil/v0.2.0",
         },
@@ -397,7 +418,7 @@ describe('http (batch)', () => {
     ).toMatchInlineSnapshot(`
       [
         {
-          "id": 92,
+          "id": 94,
           "jsonrpc": "2.0",
           "result": "anvil/v0.2.0",
         },
@@ -406,7 +427,7 @@ describe('http (batch)', () => {
             "code": -32602,
             "message": "Odd number of digits",
           },
-          "id": 93,
+          "id": 95,
           "jsonrpc": "2.0",
         },
       ]
@@ -423,7 +444,7 @@ describe('http (batch)', () => {
     ).toMatchInlineSnapshot(`
       [
         {
-          "id": 95,
+          "id": 97,
           "jsonrpc": "2.0",
           "result": "anvil/v0.2.0",
         },
@@ -432,7 +453,7 @@ describe('http (batch)', () => {
             "code": -32601,
             "message": "Method not found",
           },
-          "id": 96,
+          "id": 98,
           "jsonrpc": "2.0",
         },
       ]
diff --git a/src/utils/rpc/http.ts b/src/utils/rpc/http.ts
index c4a8342fbe..963ffbd846 100644
--- a/src/utils/rpc/http.ts
+++ b/src/utils/rpc/http.ts
@@ -140,7 +140,7 @@ export function getHttpRpcClient(
         if (err instanceof TimeoutError) throw err
         throw new HttpRequestError({
           body,
-          details: (err as Error).message,
+          cause: err as Error,
           url,
         })
       }