Cryptococcus neoformans var. neoformans was isolated from domestic dust in 54% of houses occupied or recently occupied by AIDS+ cryptococcosis patients and in 20% of control houses randomly chosen in Bujumbura, Burundi. It was not isolated from wards of similar patients in the University Hospital. This seems to prove that patients could not contaminate their own environment and that the presence of C. neoformans var. neoformans had another origin. In 40% of the cases, patients admitted contact with pigeons in the city and pigeon coops are frequently positive. We are convinced that the pigeon coops of the city play a part in the contamination of HIV+/AIDS patients; however, some patients denied any contact with pigeons and in these cases, the only possible source of contamination identified thus far is domestic dust, although the origin of the yeast remains unknown