Many Western children with congenital heart disease (CHD) show significant growth retardation. In this study postnatal growth was examined in Chinese children with symptomatic CHD in Hong Kong, in relation to their diagnosis and the time of surgery. 363 children of four years old or younger, who were admitted at Grantham Hospital, Hong Kong, in 1994 and 1995, were subdivided into six diagnostic categories and categorised into cyanotic and acyanotic groups. While a reduced birth weight SDS was present in 18% of patients, at the time of operation approximately 40% of them had subnormal weight and height values. Girls were more impaired in weight and weight-for-height than boys (-1.90 SDS vs -1.52 SDS, and -0.90 SDS vs -0.46 SDS, respectively). Children with acyanotic lesions were more affected in growth than those with cyanotic lesions, but they were also operated on at an older age than children in the latter group. Left to right shunt and common intracardiac mixing were particularly associated with wasting; transposition of the great arteries and pulmonary outflow tract obstruction with stunting; while children with left ventricular outflow obstruction revealed a proportional growth retardation in weight and height. Age at operation did not seem to have an independent effect on postnatal growth in children with CHD. As with Western children, growth retardation is a common feature in Chinese children with symptomatic cardiac defects. Haemodynamics, age at operation and nutritional influences are discussed as potential aetiologic factors.