We followed 40 girls who had undergone antireflux surgery (the Politano-Leadbetter technique) at the mean age of 5.2 years until they reached a mean age of 9.5 years. Each girl was matched with a control. The pairs were matched for age at the onset of urinary tract infections and time of operation or selection, number as well as grade (1 to 3) of severity of the preoperative episodes and grade (II to IV) of reflux. Followup time for each member of the pair was identical. Postoperatively, the incidence of pyelonephritic urinary tract infection episodes (grade 3) was significantly less (p less than 0.01) among the operated than the nonoperated cases (9 versus 29), while the number of symptomatic lower urinary tract infections (grade 2) was virtually the same (14 versus 19) in both groups. The operated cases had more asymptomatic bacteriuria (26 versus 12 episodes) so that the total numbers of episodes of bacteriuria (grades 1 through 3) were similar in both groups. Antireflux surgery did not prevent the progression of pyelonephritic renal scarring, which continued equally in operated and nonoperated cases.