Caudal regression syndrome (CRS) is a rare complex abnormality, characterized by agenesis of the sacrum and lumbar spine, with lower limb neurological deficit and accompanying deformities of the pelvis, lower extremities, genitourinary, gastrointestinal and cardiac systems. Pregnancies complicated by insulin treated diabetes carry higher risk of fetal CRS than non-diabetic pregnancies. Three dimensional (3D) and four dimensional (4D) ultrasound may assist in early detection of CRS. We report a case of CRS diagnosed by 3D and 4D ultrasound examination at 14 weeks of gestation in a diabetic patient.