Background: In patients undergoing colorectal cancer surgery, skeletal muscle depletion (sarcopenia) is associated with impaired postoperative recovery and decreased survival. This study aimed to determine whether skeletal muscle depletion can predict postoperative complications for patients undergoing cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) for peritoneal carcinomatosis of colorectal cancer. Methods: All consecutive patients with an available preoperative computed tomography (CT) scan who underwent CRS-HIPEC for peritoneal carcinomatosis of colorectal cancer in two centers were analyzed. Skeletal muscle mass was determined using the L3 muscle index on the preoperative CT scan. The cutoff values defined by Prado et al. were used to classify the patients as sarcopenic or nonsarcopenic. Results: Of the study’s 206 patients, 90 (43.7 %) were classified as sarcopenic. The sarcopenic patients underwent significantly more reoperations than the nonsarcopenic patients (25.6 vs. 12.1 %; p = 0.012). The mean L3 muscle index was significantly lower for the patients who experienced severe postoperative complications than for the patients without severe postoperative complications (85.6 vs. 110.2 cm2/m2; p = 0.008). In a multivariable logistic regression model, L3 muscle index was the only parameter independently associated with the risk of severe postoperative complications (odds ratio 0.93; 95 % confidence interval 0.87–0.99; p = 0.018). Conclusion: Skeletal muscle mass depletion, assessed using CT-based muscle mass measurements, is associated with an increased risk of severe postoperative complications in patients undergoing CRS-HIPEC for colorectal peritoneal carcinomatosis and could therefore be used in preoperative risk assessment.