Caudal regression sequence (CRS) is a rare congenital defect of the lower spinal segments and the neural tube. Motor symptoms as well as neurological deficits and loss of bladder and bowel function are usually present. CRS is also associated with anomalies in other systems such as the gastrointestinal and genitourinary tract. Etiology and pathogenesis are poorly understood.A newborn presented with anomalies of the spinal column (lumbosacral) with absence/hypoplasia of the 12th thoracic and first lumbar vertebral anomaly body. Bladder and bowel initially were functional. MR-angiography exhibited an anomaly of the unpaired vessels originating from the aorta, a likely relict of a persisting vitelline artery. These findings indicate a potential vascular genesis of CRS, much as in sirenomelia.