Maintenance fluids following major operations in children are typically administered with a continuous rate. We hypothesized that administering fluids as intermittent boluses is more physiologic and could limit post-operative fluid volume, thereby avoiding harmful effects of excess fluid. We retrospectively reviewed children aged 1-21 admitted after an elective major abdominal or thoracic operation from 2015 to 2021. We excluded non-elective operations and patients receiving peri-operative enteral or parenteral nutrition. We analyzed total fluid volume at 0-24, 24-48, 48-72, and 72-96h, time to regular diet and discharge, and end-organ complications. We identified 363 patients, of which 108 received intermittent boluses and 255 continuous fluids. Bolus group patients received significantly less fluid up to 72h post-operatively with average rates of 0.49mL/kg/h vs 0.86mL/kg/h at 0-24h (p << 0.01), 0.57mL/kg/h vs 1.46mL/kg/h at 24-48h (p << 0.01), and 0.50 vs 0.92mL/kg/h at 48-72h (p << 0.01). Additionally, the bolus group maintained adequate urine output, tolerated a regular diet sooner (2.08days vs 2.51days; p = 0.0023) and averaged a shorter hospital stay (3.12 vs 4.14days; p = 0.004). There was no difference in adverse effects between the two groups. Utilizing intermittent boluses reduces the volume of maintenance fluids administered and may lead to a faster time to regular diet and discharge. IV. Retrospective review.