Sotos syndrome is an excessive growth syndrome and is characterized by macrocephaly, typical facial appearance and mental retardation. The majority of cases are sporadic, autosomal dominant inheritance pattern matching families have been reported. Syndrome responsible for gen encodes the nuclear receptor-binding SET domain1 (NSD1) protein. This rare genetic syndrome firstly described by Sotos et al. in 1964 at five cases with excessive height, acromegalic appearance and mild mental retardation. Hairline high forehead, macrocephaly, frontal bossing, long and thin face, frontotemporal hair sparseness, down slanting palpebral fissures and prominent mandible creating characteristic facial appearance and advanced bone age and varying degrees of mental retardation are other diagnostic criteria. Cardiovascular, central nervous system and genitourinary system anomalies may be associated with syndrome. In this case report we presenting a case who admitted to our clinic because of the rapid growth and mild mental retardation and diagnosed with Sotos syndrome for emphasize the importance of growth monitoring.