Persistent patent ductus arteriosus (PDA) and clinically silent PDAs are relatively common congenital cardiac defects in humans. We report here the occurrence of symptomatic PDA in adults from a colony of genetically epilepsy-prone rats (GEPRs). Affected rats displayed severe ventral edema. Echocardiography revealed PDA in several animals. Necropsy findings included cardiomegaly, hepatic hyperemia and centrilobular necrosis indicative of passive congestion, and vascular changes consistent with pulmonary hypertension. All affected rats were descendants of one of two brother-sister breeding pairs established from a single litter in April 2000. Clinically silent PDAs were also detected in the colony. Histological examination of the ligamentum arteriosus showed normal vascular tissue in asymptomatic GEPR and Sprague-Dawley rats. PDAs are likely to have a genetic component in the GEPR colony and may provide a novel model for the study of pathogenesis and therapy of this condition.