Four patients with Xeroderma pigmentosum are reported: 2 diagnosed following the development of multiple cutaneous tumours, and 2 at an earlier state. The repair synthesis of DNA after ultraviolet radiation was reduced in 3 and normal in 1 patients. Para-aminobenzoic acid (PABA) was used topically as sunscreen; for those intolerant to PABA, alternatives are given. 5-fluoro-uracil had satisfactory effect against actinic keratoses. Two patients had associated neurologic and mental abnormalities compatible with deSanctis-Cacchione syndrome, a Xeroderma pigmentosum variant.