Cancer immunotherapy has gradually changed the prognosis of cancer patients. Recently, much evidence including novel antibodies that can close T cell barriers has indicated that immunotherapy is successful in certain patients. A shortage of dietary amino acids decreases animals and humans immunity to diseases. Amino acids regulate (1) T lymphocytes, B lymphocytes, natural killer cells and macrophages activation; (2) the redox state of the cell and gene; and (3) antibodies, cytokines and other cytotoxic substances production. Some amino acids, such as arginine, histidine and tryptophan strength the immune system. These amino acids are found in some meals, such as soybean meal, peanut meal and cottonseed meal, and in some cereal grains, such as corn, wheat middling, rice bran, and rice mill feed. In this review, we summarize the role of three important amino acids (Arginine, Histidine and Tryptophan) in the enhancement of body immunity.