The prevalence of malnutrition in cancer patients is between 20% and 40% at the time of diagnosis, increases to 80% in late stages and is greater in hospitalised patients. Nutritional risk screening seeks to identify malnourished patients or those at risk of malnutrition and to initiate timely nutritional recovery; this includes using indicators which require accurate interpretation. This narrative review was aimed at establishing which nutritional screening tools are most used and recommended for use in oncology, according to a search of the published pertinent literature and international bodies' guidelines, and ascertaining their impact on clinical outcomes.