Primary oxalosis is a rare disorder of oxalate metabolism, characterized by nephrocalcinosis, nephrolithiasis, and extrarenal deposition of calcium oxalate in several tissues, including the heart. We report the case of a 34-year-old man with sudden right hemiparesis and aphasia from the occlusion of the left middle cerebral artery. Clinical features and the results of laboratory investigations led to the diagnosis of primary oxalosis. Two-dimensional echocardiography disclosed the presence of massive intracardiac calcifications compatible with deposition of calcium oxalate. The absence of other causes of stroke strengthened a cause-and-effect relation between cardiac oxalosis and cerebral infarction. Consequently, cardiac oxalosis should be considered among possible occult cardiac sources of cerebral embolism.