Pentadecapeptide BPC 157 modulates sythesis of NO, has antiarrhythmic effect and protective effect on endothelium. This study was designed to investigate its effects in monocrotaline induced pulmonary hypertension in rats. It included 13 groups by 6 rats (body weight 150-200 g). Pentadecapeptide BPC 157 was given daily, either in drinking water or intraperitoneally, in two different dosages (10 μg/kg i 10 ng/kg), in cotreatment protocol day 1 - 29, while in posttreatment protocol therapeutic intervention with pentadecapeptide BPC 157 was started when the development of pulmonary hypertension had already commenced and was upheld day 15 - 29. In control groups a marked right heart hypertrophy was evident, and massive thickening of the precapillary artery smooth muscle layer was histologically apparent, with cilincal deterioration due to pulmonary hypertension during the 4. week after MCT injection, and some animals dying during this period because of right heart failure. In cotreatment protocol pentadecapeptide BPC 157 consistently prevented in all application modalities the development of pulmonary hypertension with all its manifestations, while in posttreatment therapeutic protocol BPC 157 reversed also in all application modalities the already established PAH. We conclude that pentadecapeptide BPC 157 prevents and attenuates MCT-induced pulmonary hypertension and cor pulmonale in rats.