Penicillin-resistant and multiresistant pneumococci occur throughout the world and at high prevalence in certain areas. Pneumococci resistant of cefotaxime and ceftriaxone have so far become established in Spain, South Africa and the USA, and the occurrence of such strains was recently reported in the UK. In Iceland, the first penicillin-resistant pneumococci were identified in December 1988, and by 1993 the prevalence was 20 percent. The risk factors appear to be the congregation of children at day-care centres, excessive consumption of antibiotics, and the common use of the sulphamethoxazole-trimethoprim combination (co-trimoxazole). The consumption of antibiotics in Iceland has been reduced, and the incidence of resistant pneumococci is somewhat lower than formerly.