Chronic graft-versus-host disease (GVHD) develops as a result of the immunologic response that donor T-lymphocytes generate against host tissue after allogeneic stem cell transplantation. We tried to elucidate the contribution of cardiac dysfunction to the high morbidity and mortality rates observed after GVHD. Forty patients who had undergone bone marrow transplantation were enrolled in this prospective study: 14 patients who had been diagnosed with chronic GVHD (manifestations beyond day 100 after hemopoietic cell transplantation) and 26 patients who had not. All patients had undergone baseline echocardiography before bone marrow transplantation and were monitored. After the expected period of time had elapsed for GVHD after transplantation, these patients were divided into 2 groups in accordance with whether or not they developed chronic GVHD. No significant differences were observed before bone marrow transplantation in the 2 groups' broad attributes or in their laboratory and echocardiographic findings (P >0.05). After transplantation, high-sensitivity C-reactive protein levels and erythrocyte sedimentation rates were significantly higher in the chronic GVHD group (P <0.001 and P=0.01, respectively). Mean left ventricular mass was 227 ± 32.3 g in the GVHD group and 149.3 ± 27.4 g in the non-GVHD group (P <0.001). The E/A flow rate was significantly higher in the non-GVHD group. This study shows that chronic GVHD increases left ventricular mass and impairs left ventricular diastolic function in patients who have developed chronic GVHD. In addition, it shows that inflammatory markers increase to higher levels in these patients. Comprehensive studies with larger samples are needed to more fully elucidate the cardiac effects of this disease. © 2013 by the Texas Heart ® Institute, Houston.