• Peripheral intravenous cannula use in a neonatal Intensive care unit was surveyed prospectively to ascertain the rate of complications and the factors influencing the life span of an intravenous cannula. During a three-month period in which 199 intravenous cannulas were inserted in 69 patients, only two significant infiltrations (1%) were observed in more than 5000 hours of intravenous therapy. None of the factors studied, including weight, age, type and rate of fluid administration, and type of medication (except pancuronium bromide), had any discernible effect on the functional life span of intravenous cannulas. Pancuronium was associated with a significant prolongation of cannula life span—from 30 to 50 hours. We conclude that in this setting, the rate of clinically significant complications from intravenous cannula therapy is low.