A Turkish patient with large 17p11.2 deletion presenting with Smith Magenis Syndrome: Smith-Magenis syndrome (SMS), which occurs as a result of an interstitial deletion within chromosome 17p11.2-p12, is a disorder that presents itself with minor dysmorphic features, brachydactyly, short stature, hypotonia, delayed speech, cognitive deficits and neurobehavioral problems including sleep disturbances and maladaptive repetitive and self-injurious behavior. We present a girl with full SMS phenotype. G-banding cytogenetic analysis showed normal 46,XX karyotype. Whole-genome array comparative genomic hybridization (CGH) was performed due to the severity of the phenotype and the unusual features present in the patient. An interstitial deletion in 17p11.2-p12, similar to 4.73 Mb in size was determined. Characteristic physical and behavioral phenotype strongly suggested SMS. This, to the best of our knowledge is the first patient with SMS reported in Turkey. We emphasize the need for whole genome analysis in multiple congenital abnormalities/mental retardation disorders with unusual and severe phenotypes.