Body height and height velocity were analysed in 54 children with obstructive urinary tract malformations over a mean period of 8.7 years, using new auxological methods. At the time of diagnosis, 9% of patients had a height of more than 2 standard deviations below the normal mean. Mean relative height changed significantly from the first to the last observation, the standard deviation score (SDS) increasing from -0.16 to +0.36 in patients with hydronephrosis compared with normal children (P < 0.05) and from -0.63 to +0.02 SDS in those without hydronephrosis (P < 0.005). The pathogenesis of the described growth disturbance is not clear. Stepwise multiple regression analysis pointed to a possible link between the duration of antibiotic treatment and the recovery of growth capacity, but improved growth could not clearly be attributed to any medical or surgical treatment. The synchronized average growth velocity curve was similar to that of healthy children and showed a normal pubertal spurt. Final height and target height calculated from parents' height differed only slightly from that of the normal population.