A routine pregnancy ultrasound examination of a 30-yr-old, multiparous, common bottlenose dolphin, Tursiops truncatus, detected an approximately 16-wk (gestational age) fetus with an omphalocele, an abdominal wall defect at the base of the umbilical cord. Throughout the pregnancy, ultrasound allowed for identification of the omphalocele contents, which included a portion of the liver and intestinal loops. The maximum diameter of the omphalocele was 11.4 cm at an estimated 51-wk gestation. Color Doppler was utilized to study the blood flow within the omphalocele as well as diagnose an associated anomaly of the umbilical cord, which contained three vessels instead of four. Gross necropsy and histopathology confirmed the ultrasound diagnoses. This is the first report of an omphalocele in a T. truncatus fetus, and the first report of a fetal and umbilical cord anomaly diagnosed with ultrasound in a cetacean.