Smith-Lemli-Opitz syndrome (SLOS) is an autosomic recessive metabolic affection. Children affected by SLOS exhibit a defect in cholesterol biosynthesis associated with a high concentration of cholesterol precursor 7 dehydrocholesterol (7 DHC) and its isomers, which is due to an enzymatic block at the level of delta-7-DHC reductase. SLOS has been subdivided into two types on the basis of clinical severity: type I is the classic and type II is the severe one.A full term female was born from a pregnancy complicated by oligoamniosis and intra-uterine growth retardation. The neurologic status was immediately impaired with severe hypotonia, absence of reflexes, and abnormal crying. She exhibited multiple congenital anomalies with a facial dysmorphia, anomalies of members, unicornus uterus and a pyloric stenosis. Plasmatic concentration exhibited a normal cholesterolemia contrasting with an elevated level of 7 and 8 DHC. Major alimentary tract defect led to enteral and parenteral nutrition. The severe neurological defect led to death on the 16th day of life.Despite normal blood cholesterol levels that can be attributed to enteral and parenteral nutrition, the severity of clinical findings and the lethal course permit to classify this case as type II.