Protoporphyria is an inherited disorder of heme biosynthesis characterized by an overproduction of protoporphyrin in the erythropoietic and hepatic tissues, the relative contribution of which in the metabolic disorder has not been directly quantitated. Excess protoporphyrin is eliminated solely by the liver into the bile and feces. We describe the case of a patient with protoporphyria complicated by severe cirrhosis in whom liver transplantation was performed and resulted in almost complete disappearance of skin photosensitivity manifestations and reduction in the level of protoporphyrin in erythrocytes. However, the level of protoporphyrin in feces was not markedly different before and after liver transplantation, which suggests that overproduction of protoporphyrin was unchanged. These findings are consistent with the view that the diseased liver and ensuing low hepatic clearance of protoporphyrin contributed to accumulation of protoporphyrin in the body and that, at least in this patient, the role of the hepatic tissue in the overproduction of protoporphyrin was small in comparison with that of the erythropoietic tissue.