We report on the prevalence of schistosomiasis and geohelminth infections in Mali, Central West Africa, based on data from the National Schistosomiasis Control Programme of Mali (1982-1991) and from our recent surveys (1992-1993). Combined national figures and regional data are presented from both surveys. Schistosomiasis showed an overall prevalence of 30.1%, with lowest prevalence in Sikasso Region and highest prevalence in Segou Region. Ascaris lumbricoïdes (0.12%) and Trichuris trichiura (0.42%) were comparatively rare, but hookworm infections were more widespread (8.0%). No hookworm infections were detected in the arid northern Region and the highest prevalence (18.7%) was encountered in the humid south of the country. There was a significant positive relationship between the prevalence of hookworm infection and total annual rainfall per region. Overall the prevalence of concurrent infections with schistosomes and hookworms was significantly less than expected, although there were regional differences which were discussed in the light of local variations in climatic and other factors likely to affect transmission.