It is evident from the previous literature that azathioprine an immunomodulator drug used for the pharmacotherapy of inflammatory bowel disease is prone to severe myelosuppression in the susceptible population. If TPMT genetic polymorphism is there it is related to the myelosuppression related to the drug azathioprine and it is linked with the metabolism of the azathioprine. In this case, a 46-year-old male patient after a short 20-day course of azathioprine for the inflammatory disease presented with fever and swelling of the face on evaluation pancytopenia was revealed, and later on further detailed evaluation, he was diagnosed with Mucormycosis. During the hospital stay, he was treated with Posaconazole and Amphotericin b liposomal preparation for the mucormycosis, and his WBC count remained normal, but the hemoglobin level remained low at 7.2 g/dl at the time of discharge. The Initial incidence of pancytopenia induced by the azathioprine and persistence of the anemia and thrombocytopenia may be due to the administration of the posaconazole for the mucormycosis.