Abstract Background Perioperative fluid replacement is a challenging issue in surgical care. The purpose of the present study was to investigate the effect of two different perioperative hydration protocols on the outcome in patients undergoing major abdominal operations. Methods This was a prospective study involving 61 patients (42 men/19 women; mean age: 52 years; age range: 18-81 years) who underwent major abdominal operations. The study had two distinct phases: before (conventional group; administered 30-50 ml/kg per day of crystalloid fluids; n = 33) and after the implementation of a protocol of restricted use of intravenous fluids (restricted group; administered less than 30 ml/kg per day of crystalloid fluids; n = 28). The total volume of intravenous crystalloid fluids infused was recorded until postoperative day (POD) 4. Morbidity, mortality, and the length of postoperative hospital stay were the main clinical variables. Results Mortality was 4.9% (p [ 0.05 between groups). Intravenous therapy in the restricted group was terminated earlier (p \ 0.001) and the patients received 2.4 l less crystalloid fluid than did those in the conventional group from POD 1 through POD 4 (p \ 0.001). The adoption of the restricted protocol shortened the postoperative hospital stay by 2 days (p = 0.02) and diminished the morbidity by 25% (p = 0.04). Conclusions Restriction of perioperative intravenous crystalloid fluid is associated with reductions in morbidity and length of postoperative hospital stay after major abdominal operations