The occurrence of hepatic porphyrias--acute intermittent porphyria (AIP) and variegate porphyria (VP)--in Finland has been studied. During a period of 9 years 107 patients with AIP and 45 patients with VP were found. The prevalence of hereditary hepatic porphyrias was calculated to be 3.4 per 100 000 inhabitants. The patients belonged to 42 different families. Eighty-nine patients (59%) had had acute attacks, whereas 63 were symptomless latent cases. Precipitating factors, symptoms and excretion of porphyrins and their precursors did not significantly differ from what has been reported earlier from other parts of the world. A slight fragility of the skin on the back of the hands was noted in some 50% of VP patients. Abnormal sensitivity to sunlight could not be seen in a single case. However, about 50% of patients with VP showed an abnormal reaction when irradiated with artificial ultraviolet light. The difference in the skin symptoms in South African and Finnish VP patients is discussed.