Resistance is an emerging problem in human medicine and the effects of resistance are being noted on an ever-increasing scale. Whether it is treatment of nosocomial bacteremia in New York City or community-acquired dysentery in Central Africa, multiresistant organisms are diminishing our ability to control the spread of infectious diseases. Clearly, the rate at which resistant organisms develop is not solely a function of the use of antimicrobials in humans, but is also highly influenced by the use of these agents in veterinary medicine, animal husbandry, agriculture, and aquaculture, as has been emphasized at recent meetings sponsored by organizations such as Rockefeller University and the American Society for Microbiology, and in the report on bacterial resistance recently issued by the US Office of Technology Assessment. We have entered an era where both physicians and patients must take on the responsibility to use antimicrobials wisely and judiciously. Just as in the days at the turn of the century when the public was an integral part of establishing quarantines for infectious diseases, now again the public's cooperation must be sought for this latest threat to public health. The multiresistant organisms of the 1990s are a grim warning of the possibility of the postantibiotic era.