The pre- and postoperative growth patterns of 52 otherwise normal infants undergoing primary surgical closure of a large ventricular septal defect before 7 months of age were reviewed. Serial measurements of weight, length and head circumference were compiled for all patients preoperatively and in 46 long-term survivors and were expressed as Z scores (in standard deviations from the mean for age and gender). By the time of surgery at a mean age of 0.33 year, the mean weight, length and head circumference Z scores of all 52 infants were -2.9, -0.9 and -0.6, respectively, and were all significantly below normal (p less than 0.001). At a mean age of 5.7 years, the mean weight, length and head circumference Z scores of 35 patients of normal birth weight were normal or varied only marginally from those of the reference population (-0.4, -0.1 and +0.5, respectively; p less than 0.02, p greater than 0.05 and p = 0.008, respectively) and did not differ significantly in any variable from those of 44 normal siblings. However, among 11 infants with a low birth weight, all three variables remained abnormal at long-term follow-up when compared with the reference population (-1.7, -1.7 and -0.9, respectively; p less than 0.001 for each) and 22 normal siblings (p less than or equal to 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)