Abstract: Sixteen patients with PCT are presented. It was suggested that hegatopathy was the most important etiologic factor in this series. As compared with other types of porphyrias, the onset of the disease is insidious and the history of photosensitivity is not clear. Earlyer diagnosis was usually difficult although the cutaneoua manifestation of PCT presented characteristic features. The diagnosis was confirmed by porphyrins determination. Quantitative assay and chromatographic analysis of urinary porphyrins were useful in the classification of the porphyrias.