diff --git a/components/layout/Header.test.tsx b/components/layout/Header.test.tsx
new file mode 100644
index 000000000..b9fa8c64f
--- /dev/null
+++ b/components/layout/Header.test.tsx
@@ -0,0 +1,86 @@
+import * as React from 'react';
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { render, screen, fireEvent, act, waitFor } from '@testing-library/react';
+import { Header, NavLink } from './Header';
+import { usePathname } from 'next/navigation';
+
+// Mock next/navigation
+vi.mock('next/navigation', () => ({
+  usePathname: vi.fn(),
+}));
+
+// Mock TransitionLink to render standard anchor tag and forward all props
+vi.mock('@/components/ui/TransitionLink', () => ({
+  TransitionLink: ({ children, href, onClick, ...props }: any) => (
+    <a href={href} onClick={onClick} {...props}>
+      {children}
+    </a>
+  ),
+}));
+
+// Mock next/image
+vi.mock('next/image', () => ({
+  default: ({ src, alt, ...props }: any) => <img src={src} alt={alt} {...props} />,
+}));
+
+// Mock LanguageSwitcher
+vi.mock('./LanguageSwitcher', () => ({
+  LanguageSwitcher: () => <div data-testid="language-switcher" />,
+}));
+
+describe('Header Dropdown Navigation TDD', () => {
+  const mockNavLinks: NavLink[] = [
+    {
+      label: 'Home',
+      url: '/',
+    },
+    {
+      label: 'Leistungen',
+      url: '/leistungen',
+      children: [
+        { label: 'Kabelbau', url: '/leistungen/kabelbau' },
+        { label: 'Bohrtechnik', url: '/leistungen/bohrtechnik' },
+      ],
+    },
+  ];
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('closes the dropdown menu immediately after a page navigation occurs', async () => {
+    // 1. Set initial pathname
+    let currentPath = '/de';
+    vi.mocked(usePathname).mockImplementation(() => currentPath);
+
+    // 2. Render Header
+    const { rerender } = render(<Header navLinks={mockNavLinks} />);
+
+    // 3. Hover over "Leistungen" menu item to open dropdown
+    const leistungenNavItem = screen.getByText('Leistungen');
+    const navItemContainer = leistungenNavItem.closest('.group');
+    expect(navItemContainer).toBeTruthy();
+
+    act(() => {
+      fireEvent.mouseEnter(navItemContainer!);
+    });
+
+    // 4. Assert dropdown is open and children are rendered
+    expect(screen.getByText('Kabelbau')).toBeTruthy();
+    expect(screen.getByText('Bohrtechnik')).toBeTruthy();
+
+    // 5. Simulate page navigation by changing the path
+    currentPath = '/de/leistungen/kabelbau';
+    
+    act(() => {
+      // Trigger pathname hook change and force rerender
+      rerender(<Header navLinks={mockNavLinks} />);
+    });
+
+    // 6. Assert dropdown is closed (children are not in the document)
+    await waitFor(() => {
+      expect(screen.queryByText('Kabelbau')).toBeNull();
+      expect(screen.queryByText('Bohrtechnik')).toBeNull();
+    });
+  });
+});