BACKGROUND: this study aimed to describe the clinical, behavioral, cognitive and communicative features of subjects with Smith-Magenis Syndrome genetic diagnosis. PROCEDURES: the subjects were two males, 09 and 19 year old. We performed a clinical and laboratory genetic evaluation (FISH assay using probes for the region 17p11.2). The psychological evaluation consisted of behavioral observation and application of the Wechsler Intelligence Scale. Speech evaluation was performed by means of formal and informal procedures and peripheral hearing evaluation. RESULTS: the clinical genetic analysis showed the phenotypic characteristics of Smith-Magenis syndrome, confirmed by laboratory evaluation. The psychological evaluation revealed the peculiar phenotype behavioral of Smith-Magenis syndrome and confirmed the moderate intellectual disabilities in two subjects. Speech evaluation showed changes in language performance, with changes in phonological, semantic, syntactic and pragmatic levels and psycholinguistic skills, interfering with communication and learning skills. The hearing test showed peripheral hearing within normal parameters. CONCLUSION: the multidisciplinary approach made easier the description of clinical, behavioral, cognitive aspects, belonging to the behavioral phenotype of Smith-Magenis syndrome and showed that these changes have severe oral language alterations in skills and psycholinguistic processing of visual and auditory information with remarkable consequences on the development of communicative skills and learning processes.