Necropsy of an Atlantic bottlenose dolphin (Tursiops truncatus) neonate that stranded dead on Folly Beach, Charleston County, South Carolina, USA, on 17 November 2007, revealed multiple congenital heart malformations. Cardiac anomalies included a hypertrophic right ventricle, ventricular septal defect (VSD), aortic dilation, atrial septal defect (ASD) between a functionally common atrium and a left atrial remnant, subvalvular pulmonic stenosis, and a hypoplastic pulmonary artery and mitral valve. Few incidences of abnormal cardiac development in cetaceans have been published. The case study serves to document a novel congenital heart malformation not previously reported, to our knowledge, in free-ranging bottlenose dolphins.