Abstract: In this trial the effects of the crude protein contents of the fattening concentrates on the fattening performance in the Turkgeldi lambs were investigated. Twentyseven Turkgeldi male lambs (weaned 2-2.5 mounts of age) were allotted randomly by weight in the three groups at the beginning of the trial. Animals in each trial groups were fed individually with trial concentrates (G1; 13.34% CP, 2510 kcal ME kg-1, G2; 14.56% CP, 2530 kcal ME kg-1, G3; 15.85% CP, 2560 kcal ME kg-1) and the concentrates were given ad libutum levels for a 56 days. Also 100 g/day sun crude hays were given per animal during the fattening period. Concentrates were given three times a day and any food remaining in the troughs were removed and weighted before the morning feeding. Live weights of the animals were recorded every two weeks interval. Average live weights at the end of the trial, average daily gains, average feed intake and feed efficience ratio of the trial groups were founds as 40.40 ± 1.586, 38.73 ± 0.877, 38.14 ± 1.757 kg; 344.31 ± 15.224, 319.69 ± 12.959, 306.56 ± 15.411 g; 1.46 ± 0.015, 1.45 ± 0.010, 1.41 ± 0.013 kg and 4.44 ± 0.214, 4.83 ± 0.231, 4.98 ± 0.302 kg for the groups of G1, G2 and G3, respectively. There were no significant differences between the groups with respect to live weights, daily gains and feed efficience ratios, although the differences about daily feed intake values between trials were found significantly (p<0.05).