This experiment was conducted to study the effects of dietary glutamine supplemental level on growth performance, nitrogen metabolism and jejunum mucosal enzyme activities of growing Rex rabbits. Two hundred weaned Rex rabbits were randomly assigned to 5 groups with 40 replicates in each group and each replicate contained 1 rabbit. Rabbits in 5 groups were fed experimental diets supplemented with 0, 0.3%, 0.6%, 0.9% and 1.2% glutamine, respectively. The experiment lasted for 7 days for adaptation and 60 days for test. The results showed as follows: under the condition of no significant difference in initial body weight (P>0.05), dietary glutamine supplemental level did not significantly affect average daily intake (ADI), average daily gain (ADG) and feed/gain (F/G) of growing Rex rabbits (P>0.05). With the increase of dietary glutamine supplemental level, the average daily gain (ADG) tended to be increased firstly and then decreased, while the feed/gain (F/G) showed the opposite tend, and the highest ADG and the lowest F/G both appeared in 0.9% glutamine group. Dietary glutamine supplemental level had significant effects on fecal nitrogen (P=0.004 8), digestible nitrogen (P=0.008 1), retention nitrogen (P=0.005 3), nitrogen apparent digestibility (P=0.000 9), nitrogen utilization rate (P=0.008 1) and nitrogen biological value (P=0.002 3), but had no significant effects on urine nitrogen and nitrogen intake of growing Rex rabbits (P>0.05). The values of the lowest fecal nitrogen and the highest digestible nitrogen, retention nitrogen, nitrogen apparent digestibility, nitrogen utilization rate and nitrogen biological value appeared in 0.9% glutamine group. Dietary glutamine supplemental level had a significant effect on the apparent digestibility of methionine (P=0.001 0), cystine (P=0.006 3), glutamic acid (P=0.010 6) and proline (P=0.000 1), but had no significant effect on the apparent digestibility of other amino acids of growing Rex rabbits (P>0.05). Dietary glutamine supplemental level had significant effects on the activities of maltase (P=0.010 8), ornithine transaminase (P=0.002 9) and glutamate synthase (P=0.007 6) in jejunal mucosa, but had no significant effects on the activities of sucrase and lactase in jejunal mucosa of growing Rex rabbits (P>0.05). Considering all indices of this experiment, the appropriate glutamine supplemental level in the diet of growing Rex rabbits is 0.9%.