Porphyria cutanea tarda (PCT), the most common porphyria disease, is characterized by blistering and skin fragility of sun-exposed skin. The symptoms are caused by lowered activity of uroporphyrinogen decarboxylase (URO-D) resulting in accumulation of water-soluble porphyrins in the skin. Most PCT cases are sporadic but can be familiar due to mutations in the URO-D gene located on chromosome number 1. The disease may be exacerbated by environmental factors. Iron accumulation is a characteristic finding and there is an association to hereditary haemochromatosis. Therapeutic venesection reduces the iron load and the uroporphyrins are mobilized by treatment with hydroxychloroquine. An increased risk of liver cirrhosis and hepatocellular carcinoma may presumably be reduced by early diagnosis and treatment.