The newborn nursery is a frequent site of epidemics of infectious disease. The unique susceptibility of neonates to colonization, their intimate exposure to hospital personnel, and their frquent contact with possibly contaminated inanimate objects are major factors contributing to the risk of nursery epidemics. Most of the epidemics described have been caused by bacteria; the role of viruses in nosocomial infections is not well defined but is undoubtedly greater than presently appreciated. All bacteria implicated in nursery epidemics have the capacity to survive or even multiply in the environment or on human skin or to cause gastrointestinal disease. Analysis of the etiologic bacteria, the epidemiology of outbreaks studied, and extensive clinical research indicate that bacterial transmission in this setting occurs primarily by manual contact and very infrequently by the respiratory route. The cornerstone of a program to prevent infectious diseases in the nursery consists of active, disease-oriented surveillance by specially trained personnel; microbiologic surveillance is important only when specifically indicated. Practical technical considerations for prevention of infectious diseases in nurseries are available. Programs to eradicate an ongoing epidemic must be individualized.