The experimental  designed to measure the effect of darkening programs on growth rates and some blood parameters in broiler chicks. Six hundred Ross308 chicks Wing-banded at 1-day old were divided into four trail groups, each with 3 replications. The chicks were raised on ground litter containing sawdust. Chick's were subjected to four darkness program: Treatment 1, serviced as a control (24 light + zero dark), Treatment 2 (18 L + 6 D continues when chicks arrived 150 g), Treatment 3 (1 hour of darkness at 2^ndday, 2 hours of darkness at the start of the 2^nd week, 3 hours of darkness at the start of the 3^th week, 4 hours of darkness at the start of the 4^th week and 5 hours of darkness at the start of the 5^th week) and Treatment 4 (1 hour of darkness from the 4^th day until the 7^th day, 4 hours of darkness from the 8^th day until the 14^th day, and 6 hours of darkness from the 15^th day until the 30^th day). The results indicated that, the positive effect of the darkness schedule program which used in the experimental trail is treatment four.