The "anorectic syndrome" of patients with malignant diseases is a symptom complex consisting of loss of appetite, aversion against food and disturbances of taste and smell. Anorexia is defined as a decrease of nourishment below 80 % of the usual food intake. Occurrence of anorexia depends on the type and location of the tumor and on tumor stage. About 40 % of tumor patients suffer from anorexia already at the time of diagnosis. The highest prevalence is seen in advanced tumor stages the etiology of anorexia is multifactorial. The causes mentioned include food aversion, disturbances of taste, gastrointestinal disorders, pain, treatment sequelas, consequences of metabolic disturbances, effects and interactions of cytokines, neuropeptides and neurotransmitters, reduced exercise as well as psychological factors and conditioned aversions. Treatment options of anorexia consist of nutritional measures like "preference guided nutrition" considering the patients individual aversions and preferences. Drugs recommended for treatment are procinetic agents, corticosteroids, gestagens or cannabinoids