This study aimed to asses the different light intensities’ effect on performance, serum biochemical Variables, and behavior of broiler chickens. 1200 newly hatched broiler chicks were randomly assigned to 1 of 6 light intensity treatments in 24-floor pens of 4.2 m* per pen at 42 days. The treatments consisted of 5, 10, 20, and 30 lux as constant during the whole study and the subsequent changes of light intensity were 30-20-10 and 20-10-5 lux that was altered after each rearing period. The results showed that body weight gain, feed intake, and FCR were unaffected by the treatments at 11, 25, and 42 days and overall period of 0 to 42 days of age. The serum biochemical parameters did not alter by the treatments. When the behavioral expressions were assessed during the entire study, light of varying intensities affected time spent on sitting, standing and pecking activity. Spending less time in an inactive behavior (sitting plus standing) was observed under 30 lux, while spending more time in an active behavior (walking plus pecking) was observed under the 20-10-35 lux treated group. Thus, the results obtained from the study suggested that growth performance and serum biochemical constituents did not differ with variations of light intensity, but varying light intensities had executed minor effects on the behavior of broilers. It can also be concluded that constant light intensity of not more than 5 lux or subsequent changes in light intensity could be applied in broiler farms without any adverse effects.