A cohort of 48 children with Noonan syndrome, with a mean age of 9 years 10 months (SD 3y 7mo; 28 males, 20 females), was recruited from a national study. Children were assessed using the Wechsler Intelligence Scales and Test of Motor Impairment-Revised (TOMI-R). The Piers-Harris Self-evaluation Questionnaire was also completed in a subgroup of age-appropriate children. Children's parents and teachers completed the Rutter A and B scales to assess of the degree of behavioural and emotional problems respectively. Mean Full-scale IQ score was 84, and one-quarter of the participants had learning disabilities. Verbal IQ tended to be slightly lower than Performance IQ. About half of the group showed evidence of mild to moderate impairment, confirming the impression of 'clumsiness/developmental coordination disorder' on the TOMI-R. Level of self-esteem, as determined by the Piers-Harris Questionnaire, was comparable to that of a standardized population. This research has identified some characteristic psychological features in Noonan syndrome. However, a specific behavioural phenotype could not be identified.