An open, non-comparative study was undertaken to assess the safety and efficacy of a single 1 g oral dose of azithromycin in patients with uncomplicated gonorrhoea. One hundred and eighteen patients (105 male, 13 female) took part in the study. Only patients culture-positive for Neisseria gonorrhoeae were evaluated. The majority of male patients (84) had urethral gonorrhoea, but four had rectal and two pharyngeal infections. Four patients had positive cultures at more than one site (two urethral and rectal; two urethral and pharyngeal). All nine female patients had infection of the cervix only. Bacteriological eradication of N. gonorrhoeae was achieved in 76/82 (93%) patients with positive urethral cultures, 9/9 with positive cervical, 4/4 with positive rectal, and 2/2 with positive pharyngeal cultures. Twenty-two patients (18 males, four females) had concomitant chlamydial infection. Chlamydia trachomatis was eradicated in all patients who returned for follow-up assessment and in whom culture was done. Azithromycin was very well tolerated, with only two patients reporting mild-to-moderate side-effects. This study shows that single-dose azithromycin is effective in uncomplicated gonorrhoea and in mixed gonococcal and chlamydial infections.