In three randomised, multicentre studies, azithromycin treatment (1g) as a single dose was administered to patients with uncomplicated gonococcal and non-gonococcal urethritis attending STD Research Laboratories in Lagos, Jos and Ibadan; between January 1989 and December, 1990. One hundred and eighty three patients, comprising 106 males and 77 females who had infections were evaluable at the end of the treatment. Of these 71% of the N. gonorrhoeae isolates were penicillinase producers (PPNG), while 39% were non-PPNG. One hundred and fourteen (95%) of 120 patients with gonococcal urethritis including 104 cases due to penicillinase producing Neiserria gonorrhoeae (PPNG) were clinically and bacteriologically cured with a single 1g dose of azithromycin. Fifty-four (90%) out of 60 patients with non-gonococcal urethritis were cured whilst administered the same dose of azithromycin. The side effects reported for azithromycin were mainly mild and moderate gastro-intestinal complaints and there were no major abnormalities in laboratory parameters. It is concluded that azithromycin was efficacious and safe for the treatment of uncomplicated gonococcal and non-gonococcal infections and may improve patient compliance.