It is common to detect microfilariae in various cytological preparations, however there are very few case reports describing microfilariae in bone marrow aspirates. It is rarer to get bone marrow failure secondary to microfilaria in bone marrow. We report here a patient from Bihar, presented to us with prolonged fever and pancytopenia, bone marrow aspirate showed microfilaria. Treatment with DEC and albendazole resulted in prompt recovery.