A rare case of a giant aneurysm of the pericallosal artery, evaluated by computed tomography, magnetic resonance imaging, and angiography, is reported, and the other 7 cases in the literature are reviewed. Giant aneurysms are exceptional in the distal segments of the anterior cerebral arteries, and may simulate a callosal tumor or hematoma on computed tomographic scan. The clinical, radiological, surgical, and pathological findings of giant aneurysms of this location are discussed and the other reported cases are analyzed. The role of magnetic resonance imaging in diagnosing and characterizing giant aneurysms is stressed.