Substantial rises in anal cancer incidence have been registered over the last few decades in the USA and a few Nordic countries. Incidence trends in the Swiss population of Vaud (about 602,000 inhabitants) over the period 1979-2001 were considered. Rates were around 0.3-0.5 per 100,000 men (age-standardized, world population) and 1.1-1.4 per 100,000 women, in the absence of any consistent trend over time. The epidemiology of anal cancer appears therefore different in this Swiss population as compared with North America and northern Europe. [authors]