KBG syndrome, described by Herrmann et al. in 1975, is characterized by macrodontia and dental anomalies, short stature, dysmorphic facial features, mental retardation, and skeletal anomalies. Since then, more than 30 additional cases have been reported, and inheritance has been consistent with an autosomal dominant pattern, despite a disproportionately high number of affected males (males:females = 24:10). We report a case of identical twins that presented with short stature, seizure disorder, and mental retardation. Additional findings included triangular facies, prominent ears, down-slanting palpebral fissures, macrodontia and brachydactyly. Radiographs showed a significant delay in bone age. Chromosome studies were normal and metabolic work-up was negative. No other family members were similarly affected. We have reviewed the cases reported to date and found that no formal criteria exist to diagnose this syndrome. What we did find was that the majority of cases were found to have macrodontia of the upper central incisors (100%), characteristic facies (80%), short stature (75%), mental retardation (73%), delayed bone age (78%), hand anomalies (76%), and/or costovertebral anomalies (78%). Other, less common features, included oligodontia, hypoplastic enamel, strabismus, seizure disorder, and syndactyly. Based on our review, we recommend the diagnosis of KBG syndrome in any patient presenting with macrodontia of the upper central incisors and three of the following: central nervous system involvement, post-natal short stature, characteristic facial dysmorphisms, hand anomalies, costovertebral anomalies, delayed bone age, and affected first degree relative.