Costello syndrome (CS) was described in 1977 by Costello who reported two unrelated children with a new syndrome comprising short stature, redundant skin of the neck, palms, soles, and fingers, curly hair, papillomata around the mouth and nares, and mental retardation. Several additional cases have been reported since then.  Herein we report two patients with Costello syndrome; one of these patients had associated mesenteric cyst.