Abstract Introduction Intraoperative fluid therapy in cytoreductive surgery with hyperthermic intraperitoneal chemotherapy plays an important role in postoperative morbidity. Studies have found an association between overload fluid therapy and increased postoperative complications, advising restrictive intraoperative fluid therapy. Our objective in this study was to compare the morbidity associated with restrictive versus non-restrictive intraoperative fluid therapy. Methods Retrospective analysis of a database collected prospectively in the Anesthesiology Service of Virgen del Rocío Hospital, from December 2016 to April 2019. One hundred and six patients who underwent complete cytoreductive surgery and hyperthermic intraperitoneal chemotherapy were divided into two cohorts according to Fluid Therapy received 1. Restrictive ≤ 9 mL.kg-1.h-1 (34 patients), 2. Non-restrictive ≥ 9 mL.kg-1.h-1 (72 patients). Percentage of major complications (Clavien-Dindo grade III-IV) and length hospital stay were the main outcomes variables. Results Of the 106 enrolled patients, 68.9% were women; 46.2% had ovarian cancer, 35.84% colorectal cancer, and 7.5% peritoneal cancer. The average fluid administration rate was 11 ± 3.58 mL.kg-1.h-1. The restrictive group suffered a significantly higher percentage of Clavien-Dindo grade III-IV complications (35.29%) compared with the non-restrictive group (15.27%) (p= 0.02). The relative risk associated with restrictive therapy was 1.968 (95% confidence interval: 1.158-3.346). We also found a significant difference for hospital length of stay, 20.91 days in the restrictive group vs 16.19 days in the non-restrictive group (p= 0.038). Conclusions Intraoperative fluid therapy restriction below 9 mL.kg-1.h-1 in cytoreductive surgery with hyperthermic intraperitoneal chemotherapy was associated with a higher percentage of major postoperative complications.