Nosocomial infection remains a pressing problem of surgery and intensive care. The authors analyze the sources of infection, the factors predisposing to it, and the pathogenetic aspects. The strategy of nosocomial infection control is determined by the clinical and nosological structure and severity of patients' status. Microbiological and pharmacological studies helped the authors develop the protocols of the initial and alternative antibiotic therapy of various nosocomial complications of wound infection, abdominal sepsis, nosocomial pneumonia, and infectious toxic shock. Experience gained by the authors permitted them to recommend preventive measures decreasing the risk of exo- and endogenous infection and improving the mechanisms of patients' immunity.