Five patients with erythropoietic protoporphyria, in whom beta-carotene treatment had proved unsuccessful, were treated on 5 or 6 occasions with washed, packed red blood cell transfusions. Following the transfusions, the photosensitivity and the protoporphyrin levels in the red blood cells decreased considerably. This treatment may be useful in reducing the high protoporphyrin level in patients with a rapidly deteriorating hepatic function.