['To examine whether vesicourethral reflux diagnosed by positioned instillation of contrast (PIC-VUR) shows clinical importance by comparing the incidence rates of febrile urinary tract infection (FUTI) before and after treatment of PIC-VUR.', 'Beginning in 2001 we used a multi-institutional registry to prospectively enroll consecutive pediatric patients with a history of FUTI without VUR according to voiding cystourethrogram (VCUG) and yet who show PIC-VUR. Treatment of PIC-VUR was with prophylactic antimicrobials or antireflux surgery. The post-treatment occurrence of FUTI was tracked.', 'A total of 14 centers enrolled 118 patients (mean age, 7.2 years; range, 0.5 to 20 years). Parents self-selected the treatment of PIC-VUR as endoscopic injection (104), ureteral reimplantation (3), or antimicrobial prophylaxis (11). Study intervals surveying for FUTI before PIC (mean, 12 months; range, 1 to 17 years) and after PIC treatment (mean, 11 months; range, 0 to 3 years) were not significantly different. Overall the incidence rate for FUTI decreased significantly from 0.16 per patient per month before PIC-VUR treatment to 0.008 per patient per month after treatment (rate ratio 20; 95% confidence interval 11 to 36). The post-treatment rate of FUTI in patients treated with antibiotics versus surgery was not significantly different (rate ratio 2.5; 95% confidence interval 0.33 to 27).'] Does treatment of occult reflux lower the incidence rate of pediatric febrile urinary tract infection?