Thirty-two cases of xeroderma pigmentosum (XP) of the complementation groups C (7), D (12), E (3), I (2) and 8 variants are analyzed biochemically and clinically. There is some congruence of the cellular defects (UDS, CFA, SCE) and the clinical severity of the skin symptoms. Despite the large clinical variability within and between the complementation groups, several clinical features are to be attributed to one group or another. The most striking observation is the predominance of LMM in the D group and BCC in the mild E group as well as in the variants. This observation might stimulate research to find a cellular characteristic of the melanoma risk.