Abstract                                                                                                                                Twenty five Awassi male lambs weighing 24+ 0.92 kg and 3.5 months  of old were used to investigate the effect of three levels of protected arginine (0 , 5 and 7 g PA/h/d) supplemented contentiously (daily) or with cut twice a week (three days feeding, one day cut) on dry matter intake (DMI), live weight gain (LWG), feed conversion ratio (FCR)rumen fermentation rate and blood characteristics. Lambs were divided  into five equal groups and fed randomly one of the following diets . The first group  received the basal diet, composed of concentrate diet without PA which served as the control group (D1). The other tested groups were fed randomly on one of the following diets: D1 diet   supplemented  continuously with 5 or 7 g PA /h/d  ( D2 and D3  respectively );  D1 diet supplemented with cut twice a week 5 or 7 g PA/h/d (D4 and D5 respectively).  Total daily DMI are not significantly altered by level and methods of PA supplementation. The diets supplemented with PA showed best (P<0.05) daily LWG, total gain and FCR (D2, D3, D4 and D5) versus to control diet (D1). ruminal pH and NH4-N were significantly (P<0.05) affected by levels of PA and methods of supplementation. Ruminal acetic acid are not affected, while propionic acid was significantly (P<0.05) increased  with diets supplemented with  PA. Blood parameters were pointed out to, (P<0.05) differences among treatments. Diets supplemented with PA shown higher(P<0.05)  Urea   N, cholesterol, high density lipoprotein (HDL) and glutamate oxaloacetate  transaminase (GOT) ) and lower (P<0.05) low density lipoprotein (LDL) and glutamate pyruvate  transaminase (GPT)   as compared with control diet (D1). In conclusion , supplementation of Awassi lambs diets with PA improved LWG, FCR, rumen fermentation rate and some blood parameters. Key Words: arginine, growth rate, rumen fermentation, blood parameters, lambs