Recently, an increase in incidences of urinary tract infections in uncircumcised male infants has been reported. However, determining what is the best management for the prepuce of newborns and infants is still to be solved. I investigated prospectively how much foreskins are retracted with age and what correlations it has with urinary tract infection in 122 males children below 15 years of age. Under 6 months of age, the majority of the foreskins were unretractable. As they got older, over 3 years of age, their prepuces became retractable. The incidence of bacteriuria was 11.4% in uncircumcised but none in circumcised and hypospadias. In 8 patients showing bacteriuria, their foreskins were retracted below 25% in length. Among them, 5 patients, in whom E. coli were grown in their urine, showed radiologic renal abnormalities and suffered from high fever indicating systemic infection. However, the other 3 cases infected by Proteus mirabilis in their urine complained of only local penile symptoms.