The main goal of this work was to study the parasitic infections during AIDS diarrhoea. A longitudinal study was carried out from October 2000 to November 2001 in the Hepato-Gastro-Enterology department of Gabriel Toure Hospital and in the Department of Epidemiology and Parasitic infections of Faculty of Medicine, Pharmacy and Odonto-stomatology of Bamako (Mali), concerning HIV positive patients suffering from diarrhoea. Detecting microbes in stools has been done through direct microscopic examination and according to procedures of Henricksen Poblenz Baerman, Kato Katz and the PCR. Among the 70 patients involved, the sex-ratio was 53%, the average age was 35 +/- 8.4 years. Fever weight loss, skin affections and digestive mycosis were often associated. Opportunistic infections have been relatively frequent with Cryptosporidium parvum with 20%, Isospora belli with 8.5% and Microsporidium with 11.5% of cases. Other non-opportunistic microbes were found. Death within the first two weeks seems more important in case of infection by Cryptosporidium parvum. The frequency and the danger of those opportunistic infections require their efficient diagnosis and care management.