The effect of daily oral administration of ephedrine (0, 1, 2, 4 or 8 mg kg-1 W0.75) on CARCASS characteristics of forty-four 2 yr old crossbred (Mehraban x Ghezel) fat-tailed ewes was studied. The ewes were fed a fattening ration, and received ephedrine by using a drenching gun for either 50 or 70 days. There was a significant interaction (P<0.05) between the dose and duration of the ephedrine treatment for crude protein and ether extract (crude fat) of the CARCASS meat (dry matter basis), leg meat and Longissimus dorsi area at the 12th rib. On day 70, ephedrine at a dose of 8 mg kg-1 W 0.75, resulted in an increase of 21.5% in crude protein, and a decrease of 16% in ether extract contents of the CARCASS meat (dry matter basis) as compared with the control group (P<0.05). After 70 days, all doses of ephedrine significantly increased the cross sectional area of the Longissimus dorsi muscle, as compared with the control ewes. The weight of leg meat as a percentage of slaughter weight was significantly increased on day 70 at 8 mg kg-1 W0.75. The data showed that ephedrine increased the protein, and decreased the fat content of the meat in crossbred fat-tailed ewe; a daily oral dose of 8 mg kg-1 W 0.75, administered for 70 days, was effective in changing CARCASS chemical composition.