This study is carried out to investigate the effect of the light period on milk yield and its components as well as on some blood parameters, in Alrashiedia Animal Farm, Directorate of Agricultural Researches, Ministry of Agriculture on 24 improved Awassi ewes in 2nd and 3rd lactation from 20/11/2011 to 29/1/2012. The ewes are randomly divided into 3 groups; 1st group is 24h:0 h. (light : dark) exposed to light period, the2nd 8h:16 h. of light period , while 3rd group 16h:8 h.. All ewes allocated on the same concentrate and roughages ration in addition to 5 kg / hd / day green alfalfa. Milk yield is recorded every 10 days after separation of suckling lambs from their mothers for 12 hours (9 pm to 9 am). Blood sample are taken three time (at the begging , Middle and end of the study) to calculate : total protein, albumin, globulins, cholesterol, and triglyceride. The results show that there is no significant effect of light period on milk production, the total amount of milk through the recorded periods for the three group are 10652.0,10021.0 and 11986.78gm/hd .There is no significant effect on the milk component. The blood parameters are not affected by the light :dark change . It can be concluded that the change in the light :dark period does not alter milk yield and some blood parameters in this study.