Various strains of the entomopathogenic fungi: Beauveria bassiana, Metarhizium anisopliae, Paecilomyces fumosoroseus and P. farinosus were found to be pathogenic for adult tsetse, Glossina morsitans morsitans but B. bassiana and M. anisopliae were the most pathogenic, often causing mortalities of up to 100%. Dose-mortality relationships were demonstrated for both B. bassiana and M. anisopliae and male tsetse were observed to be more susceptible to infection than females. Pure cultures of B. bassiana and M. anisopliae were isolated from haemolymph and fat body of tsetse previously exposed to fungal spores and hyphal fragments were often observed floating freely in the haemolymph. No increase in abortions was observed in female pregnant tsetse infected with B. bassiana and M. anisopliae and pupae produced by the infected females showed no increase in pupal mortality. Furthermore, when larvae were heavily dusted with spores of B. bassiana and M. anisopliae prior to pupation and incubation, no increase was observed in pupal mortality suggesting lack of fungal infection.