Nosocomial infection indicators are a reflection of healthcare quality and patient safety in hospitals. Infection indicators are calculated using surveillance programs and/or systems. Current nosocomial infection surveillance systems are based on both prevalence and incidence studies. Since 1990 the EPINE prevalence study, promoted by the Spanish Society for Preventive Medicine, Public Health and Hygiene, has developed 25 nosocomial infection indicators in hospital patients in Spain. And since 1994 the ENVIN-HELICS incidence study, promoted by the Infectious Diseases Working Group of the Spanish Society for Intensive and Critical Care Medicine and Coronary Units, has developed nine ICU-acquired infection indicators in critical patients. Participation in both surveillance systems is voluntary and has gradually increased over the years. These two control systems present the results of two different situations in the area of nosocomial infection and each complements the other; in addition, they have helped to train health professionals and to raise their awareness of nosocomial infection and patient safety. This article presents the indicators obtained in 2007 through both surveillance programs as well as their standards of reference.