We report cerebral vasculitis in 2 cocaine users who developed symptoms (transient blindness and persistent headache) while smoking "crack," followed by progressive widespread cerebral dysfunction with focal signs over the next few weeks. One patient had smoked crack exclusively, and the other also used cocaine intravenously. Sedimentation rates were elevated and HIV titers negative. Arteriography was normal in 1 patient and in the other showed multiple large-vessel occlusions without beading. Brain biopsy showed vasculitis involving small vessels in both patients. Multinucleated cells were present in the neuropil, but there were no granulomas or evidence of infection. One patient improved significantly with corticosteroid treatment, and made a good recovery. The other died despite corticosteroid and cyclophosphamide treatment.