['The purpose of the investigation was to determine the effect of fluid management on the need for perioperative antihypertensive therapy following coarctation repair.', 'Retrospective case study.', 'Pediatric intensive care unit.', 'Infants and children with repaired coarctation.', 'None.', 'Hypertension was defined as a systolic blood pressure exceeding the 95th percentile for age. Echocardiographic variables included pre- and postoperative coarctation gradients, shortening fraction, left ventricular wall stress, and velocity of circumferential shortening. Clinical variables included age, fluid input, urine output (0-72 hrs), estimated creatinine clearance, intensive care unit stay, and diuretic use. Twenty-four patients were identified and divided into two groups. Group 1 consisted of six normotensive patients (19%, 1 wk to 2 yrs) and group 2 included 18 patients (75%, 3 wks to 12 yrs) with hypertension who required antihypertensive therapy. Group 2 patients were older (37 months vs. 3 months), received more intraoperative fluid, had lower urine output with fewer patients receiving diuretics, had diuretic therapy started later, and had longer intensive care unit stays (p < .05). When compared with group 2, 83% of group 2 patients had a net positive fluid balance between 36 and 72 hrs postoperatively. There were no differences in mean pre-/postoperative coarctation gradients, systolic function, postoperative fluids, estimated creatinine clearance, or aortic cross-clamp time. Using logistic regression analysis, we found that variables independently associated with the need for antihypertensive therapy included intraoperative fluid volume, 48- to 72-hr urine output, a positive fluid balance, and the use and timing diuretic therapy (p < .05). Subgroup analysis of infants <1 yr of age revealed similar findings.'] Does postoperative fluid balance influence the need for antihypertensive therapy following coarctation repair?