The treatment for peritoneal malignancies has evolved over the years with the growing success of cytoreductive surgery combined with the use of hyperthermic intraperitoneal chemotherapy. Patients receiving this treatment are at risk for developing malnutrition not only due to the areas of tumor involvement but also due to the risk of undernutrition if nutritional interventions are not timely or fall short of their goal. Malnutrition leads to a gamut of health consequences. Understanding peritoneal malignancies, cytoreductive surgery with hyperthermic intraperitoneal chemotherapy, as well as the latest nutrition research may lead to a focus on the prevention or attenuation of the procedure's associated malnutrition risk. Reducing the effects of malnutrition in these patients is the goal of the nutrition support practitioner.