Sotos syndrome is a well-known overgrowth syndrome caused by haploinsufficiency of NSD1 gene located at 5q35. There are two types of mutations that cause NSD1 haploinsufficiency: mutations within the NSD1 gene (mutation type) and a 5q35 submicroscopic deletion encompassing the entire NSD1 gene (deletion type). We investigated detailed craniofacial, dental, and oral findings in five patients with deletion type, and three patients with mutation type Sotos syndrome. All eight patients had a high palate, excessive tooth wear, crowding, and all but one patient had hypodontia and deep bite. Hypodontia was exclusively observed in the second premolars, and there were no differences between the deletion and mutation types in the number of missing teeth. Another feature frequently seen in common with both types was maxillary recession. Findings seen more frequently and more pronounced in deletion-type than in mutation-type included mandibular recession, scissors or posterior cross bite, and small dental arch with labioclination of the maxillary central incisors. It is noteworthy that although either scissors bite or cross bite was present in all of the deletion-type patients, neither of these was observed in mutation-type patients. Other features seen in a few patients include enamel hypoplasia (two deletion patients), and ectopic tooth eruption (one deletion and one mutation patients). Our study suggests that Sotos syndrome patients should be observed closely for possible dental and oral complications especially for malocculusion in the deletion-type patients. © 2011 Wiley Periodicals, Inc.