Perioperative immunonutrition is aiming at modulating altered immunological and metabolic functions in the context of major surgery. It is defined as the supplementation of constitutionally essential substrates such as glutamine, arginine, omega-3-fatty acids or nucleotides. The application of such formula is recommended for patients undergoing major abdominal-surgical procedures and tumour surgery in the head neck area. The substitution should be given 5-7 days before and after the intervention.