OBJECTIVE To report a case of AIDS associated with penicilliosis marneffei and discriminate the morphology in bone marrow examination and cultural characteristic of Histoplasma capsulatum and Leishmania donovani.METHODS The three pathogens in bone marrow morphology and cultural characteristic were studied.RESULTS AIDS patient was often infected with P.marneffei,but we could differentiated easily from other pathogens because of its breeding by splitting up and the characteristis structure in bone marrow examination.CONCLUSIONS Isolation of the P.marneffei is the golden diagnosis standard,and the examination of bone marrow is important to diagnose P.marneffei infection.