Objective: The aim of this study was to analyze cases and determine the clinical significance of a prenatally detected single umbilical artery (SUA) in our population. Materials and Methods: All second and third trimester sonographic examinations carried out between January 2004 and September 2007 in our perinatology unit were reviewed. The postnatal results of the fetuses with SUA were obtained from the medical records and the patients. Results: From a total of 5,620 pregnant patients who were examined by ultrasound (US) scan between 15-36 weeks, a single umbilical artery was found in 45 cases, representing an incidence of 0.8%. Of these, 20 (45%) also presented with other malformations. There were six neonatal deaths, one fetal demise, and six terminations of pregnancy due to severe malformations in this group. Three cases with associated anomalies underwent surgery and one case required intensive care in the neonatal period. The only cytogenetic abnormality was trisomy 18 in one case. Six of 45 fetuses (13%) with single umbilical arteries had abnormal echocardiographic findings. In two of the fetuses associated anomalies (cleft palate and esophageal atresia) were detected after birth. In pregnancies without associated anomalies no aneuploidy was found and they were completely normal at birth and during the neonatal period. Conclusions: Scanning the umbilical cord is one of the essential parts of US examination. As the rate of cardiac malformations seen with single umbilical arteries is high, fetal echocardiography should be performed in suspected cases. The newborn should be reexamined immediately after birth due to the possibility of undetected anomalies.