In the evaluation expressed by the IARC Monographs, solar radiation is recognised to be carcinogenic to man. The principal risk factors for skin cancers are personal characteristics such as fair complexion or tendency to burn. After controlling for these factors, an association remains with exposure to solar radiation, with different patterns for various types of skin cancer. For cutaneous malignant melanoma (CMM) the evidence is based on the results of two dozen case-control studies which showed a significant positive association for intermittent exposure (overall OR: 1.7), a reduced risk for heavy occupational exposure (OR: 0.8) and an increased risk with sunburns (OR: 1.9). For basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) the evidence is based on experimental results in animals, on descriptive studies (mainly body location and geographical distribution) and on a few case-control studies. The risk pattern of BCC is similar to that for CMM, with increased risk for intermediate levels of cumulative exposure and a protection associated with higher levels. Contrary wise, low and intermediate cumulative doses have no effect on the risk of SCC, which increases exponentially with very high doses like those corresponding to a lifelong outdoor occupational exposure.