Background: Caudal regression syndrome (CRS) is a rare complex congenital anomaly which is characterized by agenesis of the sacral and lumbar spine. Pelvis, lower extremity, genitourinary, cardiac anomalies and lower extremity neurological and motor development deficits may be accompanied. The exact etiology is unclear but the maternal insulindependent diabetes mellitus (hyperglycaemia during embryogenesis seems to act as a teratogen), genetic factors, vascular hypoperfusion may play a role in the etiology. Case: A 41-year-old gravida 4, para 2, live 1, abortus 1 patient with 35 weeks of gestation. The patient had 12-year history of type 1 diabetes mellitus. In ultrasonographic examination we found the length of the bones (all the upper and lower bones) 8 weeks underdeveloped and didn’t observe the lumbar, sacral vertebrae and iliac bones. Lower extremities were crossed in froglike position, there wasn’t lower extremity movements. Due to sacral agenesia the head of the femurs were closer. Also pes equinovarum deformity, single umbilical artery, kidneys in contact at the midline were present. All of these findings indicated the diagnosis of caudal regression syndrome. Conclusion: Diabetes is increased fetal anomalities in pregnancy. Diabetic pregnancy should be more evaluated than pregnancies with no risk. Antenatal care should be done more carefully. Especially, prenatal maternal blood glucose levels and HbA1cis most important for prevention of fetal anomalities.