Severe morbidity after cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC) is, besides the obvious short-term consequences, associated with impaired long-term outcomes. The risk factors for severe morbidity in patients with peritoneal carcinomatosis (PC) of colorectal origin are poorly defined. This study aimed to identify risk factors for severe morbidity after CRS + HIPEC in patients with colorectal PC.Patients with colorectal PC who underwent CRS + HIPEC between 2007 and 2015 were categorized and compared between those with and those without severe morbidity. Risk factors were identified using logistic regression analysis. Morbidity was graded according to the Clavien-Dindo classification, with grade 3 or higher indicating severe morbidity.This study included 211 patients, of whom 53 patients (25.1%) experienced morbidity of grade 3 or higher. The identified risk factors for severe morbidity were extensive prior surgery [odds ratio (OR) 4.3], a positive recent smoking history (OR 4.0), a poor physical performance status (OR 2.9), and extensive cytoreduction (OR 1.2 per additional resection). Patients with a greater number of risk factors more often had severe morbidity and higher reoperation, readmission, and mortality rates. Furthermore, an internally validated preoperative prediction model for severe morbidity with an area under the curve of 70% was constructed.The current study identified risk factors for severe morbidity after CRS + HIPEC in patients with colorectal PC. Patients with a combination of risk factors have a substantial risk of severe morbidity and therefore should be carefully selected for CRS + HIPEC. The preoperative decision model can be a valuable additional tool in this process of patient selection.