Noonan syndrome (NS) is a highly prevalent genetic disorder (1 in 1000 to 2500 live births). Inheritance is mainly autosomal dominant. It is autosomal recessive only in a small group of patients. NS is characterized by short stature, facial dysmorphia and a variety of heart defects. Virtually no research is found on cognitive and social functioning in adult patients, although there are some indications that NS is associated with affective processing impairments, inadequate social behaviour, and higher levels of anxiety. For this reason, the present study examines a group of adult Noonan patients (n=30; mean age 27 ± 12,8) on measures of psychiatric and cognitive functioning. Neuropsychiatric and (neuro)psychological characteristics were recorded, as well as information on the patients' medical and developmental history. Data are presented on the hereformentioned aspects, including stature, genetic subtyping, cardial defects, school performance, and social adaptation, the latter aspects being discussed against the background of cognitive functioning. As to psychopathology, only in a small amount of patients (n = 4), criteria for a DSM-IV mood and/or anxiety disorder were met. However, in more than half of the patients, emotion identification and verbalisation defects were found. It is argued that this pattern of disabilities can be understood in terms of the concept of alexithymia.