Phenylpropanolamine (PPA) is the major ingredient in more than 70 over-the-counter preparations including diet pills, nasal decongestants, and the legal "look-alike" stimulants. Structurally and functionally similar to amphetamine and ephedrine, PPA has recently been associated with several neurological manifestations including psychosis, stroke, severe headache, seizures, and intracerebral hematoma. We report a case of intracerebral hematoma and subarachnoid hemorrhage in a young woman with angiographic and biopsy-proven vasculitis of the central nervous system (CNS) induced by PPA in her diet pills. From review of the literature, we distinguish drug-induced vasculitis as a separate entity from primary CNS vasculitis, both clinically and pathologically. This report should alert physicians, in general, to this potentially fatal side effect of PPA, a commonly used over-the-counter drug. Also, neurosurgeons in particular should consider the possibility of drug-induced vasculitis when faced with cases of intracerebral or subarachnoid hemorrhage without apparent cause.