Malnutrition is a relatively common, yet underdiagnosed entity that impacts patient outcomes, length of stay, hospital costs, and readmission. Acute illness in a patient already nutritionally debilitated by chronic disease may cause rapid depletion in nutritional stores. Hospitals are required to screen patient for malnutrition on admission and at regular intervals, and to develop and implement a nutrition care plan for those at risk. The plan guides how nutrition therapy is provided, monitored for adequacy and adverse effects, and assessed for achievement of nutritional goals. It encompasses the use of dietary modifications, and enteral and parenteral nutrition. Clinicians must be aware of serious but avoidable adverse effects, particularly refeeding syndrome in malnourished patient. Prior to discharge the patient should have already been transitioned from EN or PN to taking adequate amounts of calories by mouth; otherwise, careful discharge planning to educate the patient and/or caregivers, and coordinate the necessary multidisciplinary community services is necessary.