Human parainfluenza type 3 is the most common cause of bronchiolitis and pneumonia after respiratory syncytial virus. In a recent outbreak of nosocomial respiratory illness in a neonatal intensive care unit, parainfluenza type 3 virus was isolated in 6 of 17 neonates cultured (5 symptomatic patients and 1 asymptomatic patient). Eighteen of 52 nursing personnel had been ill during the previous week and concomitantly, with cough and nasal congestion. These personnel and all patient care givers were asked to submit nasopharyngeal cultures. Parainfluenza type 3 virus was recovered from 2. Glove and gown barriers and cohorting of infant patients limited further spread of the disease.