We describe a cerebral infarct caused by atrial myxoma. A 30-year-old woman with an atrial myxoma presented with a right hemisensory deficit. MRI carried out before and after removal of the myxoma, showed multiple small bilateral white-matter infarcts which increased in number up to the surgery. A lesion in the left thalamus, which enlarged and showed contrast enhancement 4 months before surgery, resembled an old cerebral infarct by the time the myxoma was removed. The number of lesions stopped increasing after surgery. We suggest that atrial myxomas should be removed even in asymptomatic patients, to prevent cerebral infarcts due to embolism of tumour or thrombus.