In children with vesicoureteral reflux (VUR) and urinary tract infection, retardation of growth and weight gain at the time of diagnosis and catch-up growth during follow-up, mostly after operating for VUR, have been reported. A controlled trial comparing the effect on growth of surgical treatment and long-term prophylactic antibiotic treatment has not been reported previously. Between 1980 and 1985, 306 children younger than 11 y with non-obstructive grade III or IV VUR, with a history of symptomatic urinary tract infection, were randomly allocated to surgical or medical treatment. Of these, 236 were followed for 10 y, 118 randomized to surgical treatment (mean age at entry 3.5 +/- 2.3 y) and 118 to medical treatment (mean age at entry 3.8 +/- 2.5 y). All children had renal function and blood pressure in the normal range. Body height, measured at start and after 1, 5 and 10 y, was transformed to standard deviation score of height for chronological age (SDSH-CA) and body weight to percentage of ideal body weight for height (%IBW). The evolution of SDSH-CA and %IBW was similar in both treatment groups (SDSH-CA: surgical: start, 0.23 +/- 1.4; 10 y, 0.40 +/- 1.0; medical: start, 0.14 +/- 1.2; 10 y, 0.44 +/- 1.2; %IBW: surgical: start, 99 +/- 9%; 10 y, 107 +/- 14%; medical: start, 98 +/- 10%; 10 y, 105 +/- 16%). While children starting the study below the age of 3 y (SDSH-CA 0.55 +/- 1.34) started significantly taller than those older than 3 y (SDSH-CA -0.1 +/- 1.39), the young ones demonstrated a significant drop in SDSH-CA during the 1st year (SDSH-CA 0.19 +/- 1.23), which was regained up to the 10th year (SDSH-CA 0.6 +/- 1.13), and the older ones steadily gained height up to an SDSH-CA of 0.28 +/- 1.05 at 10 y. During all of the study period, treatment protocol, grade of VUR, renal parenchymal scars at entrance and urinary tract infections did not influence growth and weight gain. Age at entry and gender were the only significant correlates with growth and weight gain.