Aim of Study: Cardiac complications may be observed after hematopoietic stem cell transplantation (HSCT). Despite significant improvement in supportive care, HSCT may be associated with significant morbidity and mortality. In this study, the aim was to evaluate the frequency of clinically serious cardiac complications after HSCT in our patients. Materials and Methods: This is a retrospective study. Cardiac complications were analyzed in 75 patients undergone to HSCT with physical examination, electrocardiography, echocardiography, and cardiac monitorization. Results: The median age was 12 years (range 11-16) and M/F ratio was 2/3 = 0.66. There are five patients with six complications among the retrospective cohort of 75. These were pericardial effusion in three patients, and sinus bradycardia in two patients and ventricular tachycardia in one patient. The incidence of cardiac complications among 75 patients with HSCT was 6.7%. The mortality rates of patients with and without cardiac complication were 40% and 34%, and both of them with cardiac complication had pericardial effusion. However, the cardiac complication was not found statistically significant factor on survival ( P = 0.82). Conclusion: Poor risk factors of patients, myocarditis, pericarditis, and heart failure owing to cumulative doses of anthracycline, cyclophosphamide, cytomegalovirus infection or other infections, mediastinal irradiation, and cryopreserved stem cell product with dimethyl sulfoxide may be effective on the development of cardiac complications individually. Early intervention can prevent death related to this complication.