High serum iron values with marked transferrin saturation were noted in four of 15 patients with porphyria cutanea tarda (PCT). Four others had serum iron and saturation levels near the upper limits of normal. In addition, the presence of hepatic dysfunction and the increased incidence of diabetes in this disease were confirmed. However, a relationship between the characteristic chemical and photocutaneous features of PCT and hemochromatosis could not be substantiated. The mechanisms responsible for the elevated iron values were discussed. The available evidence to date suggests increased absorption rather than reduced utilization as the cause of the abnormal iron findings in PCT. An unexplained but significant tendency to polycythemia was also noted in our series. Two patients had hemoglobin levels greater than 17.5 gm/100cc and six others had values greater than 16 gm/100cc and packed cell volumes higher than 50%, or both.