diff --git a/.changeset/nervous-pugs-boil.md b/.changeset/nervous-pugs-boil.md
new file mode 100644
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+++ b/.changeset/nervous-pugs-boil.md
@@ -0,0 +1,5 @@
+---
+"@coinbase/onchainkit": patch
+---
+
+-**chore**: Add useSwapBalances tests. By @cpcramer #982
diff --git a/src/swap/hooks/useSwapBalances.test.tsx b/src/swap/hooks/useSwapBalances.test.tsx
new file mode 100644
index 0000000000..fd5c0494ec
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+++ b/src/swap/hooks/useSwapBalances.test.tsx
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+import { renderHook } from '@testing-library/react';
+import type { Address } from 'viem';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import type { Mock } from 'vitest';
+import type { Token } from '../../token';
+import { useGetETHBalance } from '../../wallet/hooks/useGetETHBalance';
+import { useGetTokenBalance } from '../../wallet/hooks/useGetTokenBalance';
+import { useSwapBalances } from './useSwapBalances';
+
+vi.mock('../../wallet/hooks/useGetETHBalance', () => ({
+  useGetETHBalance: vi.fn(),
+}));
+
+vi.mock('../../wallet/hooks/useGetTokenBalance', () => ({
+  useGetTokenBalance: vi.fn(),
+}));
+
+describe('useSwapBalances', () => {
+  const address: Address = '0x123';
+
+  const ethToken: Token = {
+    name: 'ETH',
+    address: '',
+    symbol: 'ETH',
+    decimals: 18,
+    image: 'test.png',
+    chainId: 8453,
+  };
+
+  const usdcToken: Token = {
+    name: 'USDC',
+    address: '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913',
+    symbol: 'USDC',
+    decimals: 6,
+    image: 'test.png',
+    chainId: 8453,
+  };
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('returns ETH balance when fromToken is ETH', () => {
+    (useGetETHBalance as Mock).mockReturnValue({
+      convertedBalance: '10.0',
+      error: null,
+    });
+
+    (useGetTokenBalance as Mock).mockReturnValue({
+      convertedBalance: '0.0',
+      error: null,
+    });
+
+    const { result } = renderHook(() =>
+      useSwapBalances({ address, fromToken: ethToken, toToken: usdcToken }),
+    );
+
+    expect(result.current.fromBalanceString).toBe('10.0');
+    expect(result.current.fromTokenBalanceError).toBe(null);
+  });
+
+  it('returns USDC balance when toToken is USDC', () => {
+    (useGetETHBalance as Mock).mockReturnValue({
+      convertedBalance: '0.0',
+      error: null,
+    });
+
+    (useGetTokenBalance as Mock).mockReturnValue({
+      convertedBalance: '1000.0',
+      error: null,
+    });
+
+    const { result } = renderHook(() =>
+      useSwapBalances({ address, toToken: usdcToken }),
+    );
+
+    expect(result.current.toBalanceString).toBe('1000.0');
+    expect(result.current.toTokenBalanceError).toBe(null);
+  });
+
+  it('handles ETH balance error', () => {
+    (useGetETHBalance as Mock).mockReturnValue({
+      convertedBalance: '0.0',
+      error: 'ETH balance error',
+    });
+
+    (useGetTokenBalance as Mock).mockReturnValue({
+      convertedBalance: '5.0',
+      error: null,
+    });
+
+    const { result } = renderHook(() =>
+      useSwapBalances({ address, fromToken: ethToken, toToken: usdcToken }),
+    );
+
+    expect(result.current.fromTokenBalanceError).toBe('ETH balance error');
+  });
+
+  it('handles USDC balance error', () => {
+    (useGetETHBalance as Mock).mockReturnValue({
+      convertedBalance: '10.0',
+      error: null,
+    });
+
+    (useGetTokenBalance as Mock).mockReturnValue({
+      convertedBalance: '0.0',
+      error: 'USDC balance error',
+    });
+
+    const { result } = renderHook(() =>
+      useSwapBalances({ address, toToken: usdcToken }),
+    );
+
+    expect(result.current.toTokenBalanceError).toBe('USDC balance error');
+  });
+});