The present study was designed to investigate the effect of light regimens and vitamin D3 levels on growth performance and some carcass traits of broiler chickens. Two hundred and seventy birds were randomly assigned in factorial design (3x3). Three light regimens (24 hrs continues light, 12 hrs continues with 12 hrs flash light and 24 hrs flash light) and three vitamin levels (0 IU Vit. D3, 200IU Vit. D3 and 400IU Vit. D3). Nine treatments of 30 birds each (three replicates of 10 birds each). The birds were housed in floor pens from day one till six weeks of age. Feed and water were available ad lib. and all conditions were the same during the experimental period. The results showed that significantly affected body weight, daily weight gain and feed conversion ratio. In addition, birds reared under continuous with flash light and feed with 200 IU Vit. D3 had significantly (P≤0.05) highest in body weight, daily weight gain and feed conversion as compared to the other groups. Finally, birds reared under continuous with flash light and feed with 200IU Vit. D3 was better than the other groups.