Kilic M 1 , Tokatli A 1 , Alanay Y 2 , Kilic E 2 , Kalkanoglu-Sivri HS 1 , Dursun A 1 , Önol S 1 , Haliloglu G 3 , Utine GE 2 , Boduroglu K 2 , Coskun T 1 1 Pediatr Metab Dis, Hacettepe University, Ankara, Turkey 2 Pediatr Genet, Hacettepe University, Ankara, Turkey 3 Pediatr Neurol, Hacettepe University, Ankara, Turkey Background: Smith-Lemli-Opitz Syndrome is an autosomal recessive disorder characterized by cholesterol synthesis defect. Yet there is no current proven therapy, studies so far indicate cholesterol therapy and HMG-CoA reductase inhibitors like Simvastatin improve growth, behavior and general wellness. Methods: Our study included four patients between 31 and 71 months of ages. Results and Conclusions: Male to female ration is 1/3 and consanguinity is present in 25 percent of cases. All patients presented around 2-3 months of ages with failure to gain weight and received a diagnosis before age 1. A characteristic facial appearance, microcephaly, submucosal cleft palate, cutaneous syndactyly, mental retardation, behavioral and feeding problems, postnatal growth retardation were present in all cases; and prenatal growth retardation was seen in half of cases. Cholesterol therapy of 100 mg/kg/day was started. During follow up increase in cholesterol level was observed while 7-dehydrocholesterol level was not decreasing. Patient's parents didn't consent with Simvastatin therapy due to unknown efficiency and possible side effects. With therapy; growth parameters, head circumference increased in accordance with growth chart rates. Except for one case, none of the patients reached to the 3 rd percentile. With regard to behavior, improved skills in every area was detected albeit little.