Patients with Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML), gastrointestinal stromal tumors (GISTs) or acute lymphoblastic leukemia (ALL) are appropriate candidates for medical treatment using imatinib. Here, we report a case of imatinib-induced acute heart failure in a patient with ALL and retrospectively analyse the adverse reactions of imatinib. The patient was a 45-year man with Ph+ and bcr-abl positive (bcr-abl+) ALL. He was treated with imatinib approximately four months ago. At that time, he had no risk factors for cardiac disease, and his heart function was normal. Then, four months after starting imatinib, he manifested signs of acute heart failure. A retrospective analysis of the adverse reactions in 100 cases of leukemia patients, who took imatinib in the past three years, indicated a rare incidence of congestive heart failure among those patients. Our experience in treating the patient suggests that brain natriuretic peptide levels and cardiac doppler examinations should be monitored closely in these patients. Key Words: Imatinib, Acute lymphoid leukemia, Acute heart failure.