Twenty-six episodes of gonococcal urethritis or vulvovaginitis in 24 prepubertal patients were each treated with a single intramuscular (IM) dose of spectinomycin hydrochloride. Twenty-five episodes were treated successfully, and there were no side effects from this therapy. All tested isolates of Neisseria gonorrhoeae were susceptible in vitro to spectinomycin, and all serum levels one hour after therapy were in at least two-fold excess of the observed minimum inhibitory concentrations. Two patients had symptomatic and two had asymptomatic postgonococcal anogenital infections with Chlamydia trachomatis. A single dose of IM spectinomycin is a safe and efficacious regimen for uncomplicated gonococcal infection in prepubertal children who are penicillin-allergic or who have infections unresponsive or resistant to other antimicrobials, but it is not effective against incubating syphilis or chalmydial infection.