The Institute of Medicine's 1999 report on medical errors stated that 44,000 to 98,000 deaths occur annually because of adverse patient events, at a national cost of $17 to $29 billion. Hospital-acquired infections (HAIs) are estimated to represent 50 percent of this human and economic burden. Surveillance in combination with infection control programs can prevent up to one third of HAIs by organizing and implementing focused prevention interventions. The National Nosocomial Infections Surveillance (NNIS) system, created by the Centers for Disease Control and Prevention in 1970, establishes and monitors national benchmarks for HAI rates based on standardized definitions and validated methodology and facilitates comparative quality assessments for individual hospitals. Estimates of the burden of HAIs on hospitalized children can vary widely from less than 1 percent to greater than 20 percent, depending on the patient's host factors or extrinsic exposures, the methodology used to ascertain infections, and the denominator used to calculate rates. It is useful to have benchmark rates, such as those determined through the NNIS system, that reflect consistently collected data over time and for large populations of patients. In 1999, the Pediatric Prevention Network, a collaboration between the National Association of Children's Hospitals and Related Institutions and the Hospital Infections Program, Centers for Disease Control and Prevention, conducted the first national point prevalence surveys of HAIs in neonatal and pediatric intensive care units. The data provided by the NNIS system (incidence data) and the Pediatric Prevention Network (prevalence data) surveys are important contributors to our understanding of the epidemiology of HAIs in pediatric patients. Copyright © 2001 by W.B. Saunders Company