We report a 52 year-old man presenting with an acute considerable hair loss induced by carbamazepine (CBZ). The remarkable scalp hair loss started within a week after CBZ administration. There was no evidence of dermatitis or allergic reaction, or other cause for the hair loss. The serum concentration of CBZ was 8.6 microg/ml (therapeutic range 8-12 microg/ml). CBZ was discontinued, and the hair loss stopped within several days with new hair growth. Medication-induced hair loss is an occasional adverse effect of many drugs used for neuropsychological diseases. CBZ also induces hair loss and its frequency was reported below 2%. Only a limited number of detailed case reports describing CBZ-induced hair loss were available, and we found these cases could divide into two groups with regard to a delay in starting hair loss after administration of CBZ. In one group, the hair loss started within a week suggesting anagen effluvium and in another it started after two or three months suggesting telogen effluvium. This finding suggests the causative mechanism of CBZ-induced hair loss is not unitary.