We attempted to develop a pulmonary hypertension model in dogs by gelatin sponge embolization. We then monitored right-ventricular pressure overload by echocardiography. Gelatin sponges (Spongel®, Yamanouchi, Tokyo) were homogenized and mixed in normal saline (0.6 mg/ml). The mixture was administered via the jugular vein to general pulmonary emboli. Repeated administration of the sponges increased the mean pulmonary arterial pressure and caused right ventricular pressure overload. The degree of pulmonary hypertension was proportional to the volume of gelatin sponge injected. Echocardiography, performed both before and after embolization, proved useful assessing for the degree of right-ventricular pressure overload