Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 4 1 2019 07 16 9 13 Marzie Ghalamkari Department of Internal Medicine, Cancer Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran. Sahar Karimpour Reihan Department of Internal Medicine, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran. Nasim Khajavi Rad Department of Internal Medicine, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran. Mahsa Abbaszadeh Department of Internal Medicine, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran. 2018 10 27 2019 01 28 Aplastic anemia is characterized by bone marrow failure and pancytopenia. It could be due to autoimmune disorders, radiation, drugs, or chemicals. Drugs that mostly cause aplastic anemia include chloramphenicol, non-steroidal anti-inflammatory drugs, antiepileptic drugs, gold salts, and antithyroid drugs. Clinical sign and symptoms often result from pancytopenia that includes signs of anemia and bleeding. In some patients, fever and sepsis are seen that are due to neutropenia. Azathioprine is a purine antimetabolite, an immunosuppressive drug that causes myelosuppression and pancytopenia, especially in patients who have some degrees of TPMT (Thiopurine Methyltransferase) activity. We present a patient who admitted to our hospital with fever and pancytopenia and a history of recent azathioprine treatment. Because of delay in the recovery of pancytopenia, she was suspected of aplastic anemia, and bone marrow aspiration and biopsy were done for her. https://crcp.tums.ac.ir/index.php/crcp/article/view/231 https://crcp.tums.ac.ir/index.php/crcp/article/download/231/289