Betaine is an osmoregulatory substance obtained from some natural plant materials such as sugar beet, regulating intracellular biochemical events by attracting water. Due to this important function of betaine in water balance, it may play an important role in maintaining the body water balance of birds under heat stress. On the other hand, since betaine is a good methyl donor, some essential nutrients such as methionine and choline can be saved in the diet, or they can serve as complementary substances in the deficiency of these nutrients. Previous studies have shown that the addition of betaine can make significant contributions to the nutrition of broiler chickens in heat stress situations. The effects that may occur, especially when the body needs methyl groups, may be more pronounced. Dietary betaine supplementation increases live weight gain and breast muscle efficiency, improves feed efficiency and reduces fat content in broilers. The osmoregulatory function of betaine, immune system disorders, low immune strength, reducing respiratory alkalosis, oxidative stress and intestinal microbiome changes caused by heat stress. In this study, some evaluations were made in terms of the use of betaine in broiler diets to meet the performance and physiological needs of animals.