Ambulatory intravenous (IV) treatment is frequently prescribed to be administered every 24 hours. Institutional protocols commonly recommend flushing catheters every 8 hours. The authors sought to identify whether flushing more than once every 24 hours conferred any benefit. A retrospective review compared complication rates of different catheter flushing intervals for patients receiving IV therapy. This study investigated 111 courses of treatment for 63 patients. In 43% of the patients (48/111), complications were identified during the treatment period. Complications were less common with flushing every 24 hours (39/99, 39.4%) than with more frequent flushing (9/12, 75%) (P = .021). Indwelling peripheral IV catheters flushed once every 24 hours appear to have lower complication rates than those flushed 2 or 3 times a day.