Secretory IgA (sIgA) is an important parameter in the predisposition to recurrent urinary tract infection (UTI). We investigated whether sIgA and frequency of UTI could be positively influenced by intramuscular vaccination with inactivated uropathogenic bacteria (Solco-Urovac). Ten otherwise healthy girls aged from 5 to 11 years (mean 9 +/- 1.7 years) with recurrent UTI were immunized with Solco-Urovac by i.m. injections three times at weekly intervals. A booster injection was given after 6 months. Urinary sIgA secretory component (SC) concentration was determined by radial immunodiffusion assay. Ten other age-matched girls with UTI were not immunized. Immunization therapy caused a significant reduction in the frequency of infection and an increase in urinary sIgA SC, while in the nonvaccinated group the values remained constant.