Gonococcal arthritis, a rare complication of gonorrhoea, more frequent in women, causes polyarthritis in 75% of cases or monoarthritis. An erythematous skin rash or acute pustular rash (40%), recent signs of genital infection (75% of cases in man, less than 50% in women) suggest the diagnosis. The gonococcal nature of the arthritis is confirmed by isolation of the germ in the joint fluid, the blood and the skin biopsies. In about half the cases, these bacteriological investigations are negative, but the diagnosis remains very probable if the germ is isolated from one or other of the primary foci of the infection: ureter, cervix, vagina, rectum and even pharynx. The rapidly favourable course under antibiotic treatment with penicillin or ampicillin confirms the diagnosis. The pathogenesis of arthritis is a direct toxic action of the gonococcus on the synovial membrane and the periarticular structures. The role of circulating immune complexes recently demonstrated in gonococcemia is probably not relevant.