The role of single-dose therapy was evaluated by pooling data on 320 infants and children included in 12 clinical trials that differed from each other in many variables. Single-dose therapy achieved an overall cure rate of 89%, but varied with different antimicrobial agents. Intramuscular aminoglycosides were the best (cure rate: 96%) closely followed by trimethoprim-sulfamethoxazole or a sulfa drug with a cure rate of 90%. The cure rate with amoxicillin (75%) was significantly less. Single-dose therapy was most effective (cure rate: 90%) in well-documented lower urinary tract infections (UTIs) and slightly less effective (cure rate: 89%) among those in whom upper UTI could not be excluded. In patients with a normal urinary tract, single-dose therapy was significantly more effective (cure rate: 93%) than in the group of 36 patients with a urinary tract malformation (cure rate: 69%). Single-dose therapy can be used with confidence in patients with lower UTIs and in those with normal urinary tracts. In patients with abnormal urinary tracts and lower UTIs, single-dose therapy may be used with caution, preferably using aminoglycosides. Further studies are required to establish a definitive role of single-dose therapy in patients with urinary tract malformation.