diff --git a/packages/types/src/codebase-index.ts b/packages/types/src/codebase-index.ts
index 61009ba3011..09e5ab6b917 100644
--- a/packages/types/src/codebase-index.ts
+++ b/packages/types/src/codebase-index.ts
@@ -14,6 +14,35 @@ export const CODEBASE_INDEX_DEFAULTS = {
 	SEARCH_SCORE_STEP: 0.05,
 } as const
 
+/**
+ * List of directories that are excluded from codebase indexing.
+ * These directories are typically large and would slow down indexing.
+ * The list is shared between the indexer and the UI to provide transparency.
+ */
+export const EXCLUDED_INDEXING_DIRECTORIES = [
+	"node_modules",
+	"__pycache__",
+	"env",
+	"venv",
+	"target/dependency",
+	"build/dependencies",
+	"dist",
+	"out",
+	"bundle",
+	"vendor",
+	"tmp",
+	"temp",
+	"deps",
+	"pkg",
+	"Pods",
+	".git",
+] as const
+
+/**
+ * Pattern for hidden directories (directories starting with a dot)
+ */
+export const EXCLUDED_HIDDEN_DIRECTORY_PATTERN = ".*" as const
+
 /**
  * CodebaseIndexConfig
  */
diff --git a/webview-ui/src/components/chat/CodeIndexPopover.tsx b/webview-ui/src/components/chat/CodeIndexPopover.tsx
index 368f0395eaf..d8c218e5f89 100644
--- a/webview-ui/src/components/chat/CodeIndexPopover.tsx
+++ b/webview-ui/src/components/chat/CodeIndexPopover.tsx
@@ -12,7 +12,11 @@ import {
 import * as ProgressPrimitive from "@radix-ui/react-progress"
 import { AlertTriangle } from "lucide-react"
 
-import { CODEBASE_INDEX_DEFAULTS } from "@roo-code/types"
+import {
+	CODEBASE_INDEX_DEFAULTS,
+	EXCLUDED_INDEXING_DIRECTORIES,
+	EXCLUDED_HIDDEN_DIRECTORY_PATTERN,
+} from "@roo-code/types"
 
 import type { EmbedderProvider } from "@roo/embeddingModels"
 import type { IndexingStatus } from "@roo/ExtensionMessage"
@@ -194,6 +198,7 @@ export const CodeIndexPopover: React.FC<CodeIndexPopoverProps> = ({
 	const [open, setOpen] = useState(false)
 	const [isAdvancedSettingsOpen, setIsAdvancedSettingsOpen] = useState(false)
 	const [isSetupSettingsOpen, setIsSetupSettingsOpen] = useState(false)
+	const [isExcludedDirsOpen, setIsExcludedDirsOpen] = useState(false)
 
 	const [indexingStatus, setIndexingStatus] = useState<IndexingStatus>(externalIndexingStatus)
 
@@ -1593,6 +1598,41 @@ export const CodeIndexPopover: React.FC<CodeIndexPopoverProps> = ({
 							)}
 						</div>
 
+						{/* Excluded Directories Info Section */}
+						<div className="mt-4">
+							<button
+								onClick={() => setIsExcludedDirsOpen(!isExcludedDirsOpen)}
+								className="flex items-center text-xs text-vscode-foreground hover:text-vscode-textLink-foreground focus:outline-none"
+								aria-expanded={isExcludedDirsOpen}>
+								<span
+									className={`codicon codicon-${isExcludedDirsOpen ? "chevron-down" : "chevron-right"} mr-1`}></span>
+								<span className="text-base font-semibold">
+									{t("settings:codeIndex.excludedDirectories.title")}
+								</span>
+							</button>
+
+							{isExcludedDirsOpen && (
+								<div className="mt-2 space-y-2">
+									<p className="text-sm text-vscode-descriptionForeground">
+										{t("settings:codeIndex.excludedDirectories.description")}
+									</p>
+									<div className="flex flex-wrap gap-1">
+										{EXCLUDED_INDEXING_DIRECTORIES.map((dir) => (
+											<span
+												key={dir}
+												className="inline-flex items-center px-2 py-0.5 rounded text-xs font-mono bg-vscode-badge-background text-vscode-badge-foreground">
+												{dir}
+											</span>
+										))}
+									</div>
+									<p className="text-xs text-vscode-descriptionForeground italic">
+										{t("settings:codeIndex.excludedDirectories.hiddenDirectoriesNote")} (
+										{EXCLUDED_HIDDEN_DIRECTORY_PATTERN})
+									</p>
+								</div>
+							)}
+						</div>
+
 						{/* Action Buttons */}
 						<div className="flex items-center justify-between gap-2 pt-6">
 							<div className="flex gap-2">
diff --git a/webview-ui/src/i18n/locales/en/settings.json b/webview-ui/src/i18n/locales/en/settings.json
index b836ecbfc87..197c6bce08f 100644
--- a/webview-ui/src/i18n/locales/en/settings.json
+++ b/webview-ui/src/i18n/locales/en/settings.json
@@ -179,7 +179,12 @@
 			"baseUrlRequired": "Base URL is required",
 			"modelDimensionMinValue": "Model dimension must be greater than 0"
 		},
-		"optional": "optional"
+		"optional": "optional",
+		"excludedDirectories": {
+			"title": "Excluded Directories",
+			"description": "These directories are automatically excluded from indexing to improve performance. Files in these directories will not be indexed or searchable.",
+			"hiddenDirectoriesNote": "Additionally, all hidden directories (starting with a dot) are excluded."
+		}
 	},
 	"autoApprove": {
 		"description": "Run these actions without asking for permission. Only enable for actions you fully trust and if you understand the security risks.",