The sacral agenesis syndrome is a severe congenital abnormality consisting of agenesis of the lumbar spine, sacrum, and coccyx, as well as hypoplasia of the lower extremities. It is considered the most characteristic of all congenital anomalies associated with maternal diabetes mellitus. We describe the sonographic and radiologic findings of agenesis of the lumbosacrococcygeal spine with lower limb and genital hypoplasia in the offspring of a woman with both diabetic retinopathy and nephropathy. The diagnosis was established at 25 weeks' gestation and was confirmed by radiologic evaluation of the neonate.