The prevalence of penicillin-resistant Neisseria gonorrhoeae in black men with acute urethritis at two clinics for sexually transmitted diseases in Port Elizabeth was assessed during the latter half of 1986. Gonococcal aetiology was confirmed in 80% of 290 patients. Penicillinase-production was detected in 4.3% culture-positive cases, while intermediate penicillin resistance was demonstrated in another 28 isolates (13.9%). At least two strains exhibited high-level penicillin resistance without producing beta-lactamase. All isolates tested were susceptible to tetracycline and spectinomycin. The emergence of penicillin-resistant gonococci throughout southern Africa will require new approaches to the treatment of acute urethritis in men.