The risk for malnutrition increases with age and presence of cancer, and it is particularly common in older cancer patients. A range of simple and validated nutrition screening tools can be used to identify malnutrition risk in cancer patients (e.g., Malnutrition Screening Tool, Mini Nutritional Assessment Short Form Revised, Nutrition Risk Screening, and the Malnutrition Universal Screening Tool). Unintentional weight loss and current body mass index are common components of screening tools. Patients with cancer should be screened at diagnosis, on admission to hospitals or care homes, and during follow-up at outpatient or general practitioner clinics, at regular intervals depending on clinical status. Nutritional assessment is a comprehensive assessment of dietary intake, anthropometrics, and physical examination often conducted by dietitians or geriatricians after simple screening has identified at-risk patients. The result of nutritional screening, assessment and the associated care plans should be documented, and communicated, within and between care settings for best patient outcomes.