Kala azar was diagnosed in 45 clinically suspected cases following bone marrow smear examination and in vitro culture of the aspirate. Bone marrow aspiration smear examination revealed amastigotes in 27 cases (60%). In vitro culture of the aspirate demonstrated leishmania parasites in 44 cases (97.8%). A total of 18 cases (40%) were negative for amastigotes in smear examinations but parasites could be demonstrated by culturing the same aspirates. The in vitro culture of bone marrow is necessary to diagnose Kala azar and is strongly recommended to be performed along with the bone marrow smear examination.