Developmental and behavioural phenotype in Noonan syndrome? Noonan syndrome is characteristic by facial dysmorphology, congenital heart defects, short stature, developmental retardation and severe early feeding disorders in many cases. Data from a postal survey on physical development, feeding difficulties, developmental problems and behavioural aspects in 26 children are reported. The findings suggest developmental and behavioural difficulties in 46 per cent, but do not support the notion of a behavioural phenotype specific to Noonan syndrome. Having to cope with early surgery, feeding, developmental and behavioural problems establishes a need for psychological counseling for families receiving a diagnosis of Noonan syndrome.