As a major source of protein in the form of meat and eggs, poultry farming is critical to global food security. The aim of this study was to investigate how chickens physiologically adapt to tropical environments. This study used quantitative research with a cross-sectional approach. The study focused on three chicken breeds that are regularly raised in tropical regions: Gallus gallus, Baladi, and Hypeco. A total of 150 chickens (50 per breed). This study found substantial physiological and behavioral variations between Gallus gallus, Baladi, and Hypeco chickens in response to tropical temperatures. Hypeco hens had the highest body temperature, respiratory rate, heart rate, and corticosterone levels, showing that they are more heat stressed than other breeds............... Keywords: .........Physiological, Adaptation, Pultr, Ttropical, Climates.