Porphyria cutanea tarda (PCT), the commonest of all porphyrias, is usually characterized by blisters and fragility of skin in light-exposed areas. It can be clinically indistinguishable from other disorders including variegate porphyria and the diagnosis can only be made by rigorous biochemical analysis. PCT does not cause acute attacks of porphyria. It is usually an acquired condition caused by inhibition of the uroporphyrinogen decarboxylase enzyme in the liver. Hereditary haemochromatosis, hepatitis C virus infection, alcohol, oestrogens and a family history of PCT are the major risk factors for the condition and should be searched for specifically in all patients. Liver disease, including hepatocellular carcinoma, is common in patients with PCT, and should be investigated for at presentation by means of a liver biopsy where possible. Patients with severe hepatic pathology or longstanding untreated PCT need to be monitored for the development of hepatocellular carcinoma in the long term. Low dose twice weekly chloroquine is the mainstay of treatment, but venesection should be used in patients with severe iron overload or hepatitis C-related liver disease. Subsequently, long-term follow-up is needed in all patients to monitor for relapse.