- Hairy cell Leukaemia (HCL) is a rare chronic lymphoid hemoproliferation. Few studies have been carried out in this area in sub-Saharan Africa. Between January 1993 and December 1999, 10 cases (6 men and 4 women, average age: 43.3) of HCL were registered in the haematology service of the University hospital Centre of Brazzaville (UHCB). As far as the socio-professional and environmental risk is concerned, three patients have probably been exposed: one as a workman in wood working industry and the other two as exposed to hydrocarbons manipulation for at least ten years. Retroviral serology tests were negative for HIV and HTLV I/II. From a clinical standpoint, patients all presented large spleen, which was misinterpreted as being of malarial origin associated with severe pancytopenia. Histological and immunohistological assays were instrumental in making the correct diagnosis. Chemotherapy could not be systematically offered due to lack of means. Splenectomy was performed, and for 2 patients who were sent abroad, this was followed by administration of interferon alpha. This study once again highlights the difficulty of clinical management of malign hemopathies in sub-Saharan Africa.