Data from the Cancer Registries of the Swiss Cantons of Vaud and Neuchâtel were analysed to examine possible associations between skin cancers (including basal cell carcinoma, BCC), non-Hodgkin's lymphomas (NHL) and chronic lymphocytic leukaemias (CLL). Between 1974 and 1993, 1767 cases of NHL, 351 of CLL, 1678 of cutaneous malignant melanoma (CMM), 4131 of squamous cell carcinoma (SCC) and 10575 of BCC were registered, and contributed to a total of 120103 person-years at risk. Following NHL, 36 cases of SCC were registered compared with 5.1 expected, corresponding to a standardised incidence ratio (SIR) of 7.0 (95% confidence interval, CI, 4.9-9.7); 37 cases of BCC were observed compared with 10.2 expected (SIR = 3.6; 95% CI 2.6-5.0). Following CLL, nine cases of SCC were observed compared with 1.8 expected (SIR = 5.0; 95% CI 2.3-9.5) and nine cases of BCC were observed compared with 3.3 expected (SIR = 2.7; 95% CI 1.2-5.2). After SCC, 23 cases at NHL were observed compared with 9.0 expected (SIR = 2.6; 95% CI 1.6-3.8); after BCC, 43 cases of NHL were registered compared with 22.5 expected (SIR = 1.9; 95% CI 1.4-2.6); and after CMM, four cases of NHL were observed compared with 2.0 expected (SIR = 2.0). No significant excess of CLL was recorded following skin cancer, but the absolute numbers were small and the SIR was above unity. The findings of this study, conducted in populations with a high level of ascertainment and registration of skin cancers, confirm an excess of skin cancers including BCC, following NHL and CLL, and an excess of NHL following skin cancers. This may be related to shared aetiological factors such as U.V. radiation and associated immunosuppression. Individual-based data on the relationship between U.V. exposure and lymphoid neoplasms are needed to clarify the issue.