Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) can be associated with significant morbidity and prolonged hospital stay. Postoperative infections account for a high burden of these complications. This study aimed to assess the predictive value of postoperative C-reactive protein (CRP) levels for overall infectious complications and anastomotic leaks. This was a single-center prospective study of patients undergoing CRS and HIPEC for peritoneal metastases between 2018 and 2020 at Maisonneuve-Rosemont Hospital in Montreal, QC, Canada. CRP levels were measured daily for 10days following surgery. A comparison was made between patients with infectious complications and those without. Ninety-nine patients were included. Thirty patients had infectious complications (30.3%) and four patients presented an anastomotic leak (4%). CRP levels were significantly higher in patients with infectious complications from postoperative days (PODs) 2-10. Daily cut-off values most accurately predicted infectious complications on day 8 (94.3mg/L; area under the curve [AUC] 0.85, sensitivity [SE] 76.2%, specificity [SP] 94.7%, positive predictive value [PPV] 88.9%, negative predictive value [NPV] 87.8%; p<0.0001) and day 9 (72.7mg/L; AUC 0.89, SE95.2%, SP81.8%, PPV 76.9%, NPV 96.4%; p<0.0001). Patients with infectious complications had longer operative time, higher peritoneal cancer index, and a higher number of intestinal anastomoses, while their baseline characteristics were comparable. Measurement of CRP helps predict infectious complications following CRS and HIPEC, particularly on PODs 8 and 9. Cut-off values are more accurate after the first postoperative week, especially in ruling out infectious complications.