OBJECTIVE: To describe the epidemiology and clinical impact of respiratory viruses in a neonatal intensive care unit (NICU). STUDY DESIGN: We conducted a retrospective observational study of infants with respiratory viruses detected by multiplex reverse-transcriptase PCR from May 2012 to May 2017. The proportion of symptomatic vs. asymptomatic infants and associated morbidity were assessed. The association of infection prevention and control (IP&C) strategies and transmission was ascertained. RESULTS: Respiratory viruses were detected in 83 infants representing 86 unique episodes during which infants remained asymptomatic in 15 (17%). Of the 71 symptomatic episodes, only 45% were associated with increased respiratory and/or nutritional support. Rhinovirus/enteroviruses were most common (69%) and involved nine of 12 transmission events. IP&C strategies including restricting visitors <12 years of age and screening exposed infants were associated with decreased transmission rates. CONCLUSIONS: NICU patients can be asymptomatic carriers of respiratory viruses. Identification of such infants is important to prevent transmission in the NICU.