This report concerns an 18-year-old boy who is hemizygote for Fabry's disease. Varying degrees of nonpulsating headache crises, lasting from a few hours to several days, began when he was 16 years of age. Painful crises in the extremities, characteristic of Fabry's disease, were not present. Although only occasional, he had several episodes of throbbing headache with vomiting without aura. The meningeal signs were equivocal, although the patient had noninfectious pleocytosis, intracranial hypertension, delayed radioisotope clearance on cisternography, and multiple old cerebral infarcts. Nonsteroidal anti-inflammatory drugs, antidepressants, carbamazepine, and glycerol were of no benefit for his headache. Although its mode of action remains obscure, prednisolone was effective for treating the headache and the aseptic meningeal reaction.