This experiment was conducted to study the effects of glutamine on growth performance, serum biochemical indexes and antioxidant capacity of minks in summer. One hundred and sixty minks at the growing period were selected and randomly divided into 5 groups. Each group had 16 male minks and 16 female minks, a total of 32 replicates in each group. The minks in control group were fed a basal diet (not adding glutamine), the minks in experimental groups were fed experimental diets which supplemented with 0.2%, 0.4%, 0.6% and 0.8% glutamine on the basis of the basal diet, respectively. The experiment lasted for 8 weeks. The results showed that diet supplmented with 0.4% and 0.6% glutamine could significantly increase the average daily feed intake of female minks (P<0.05), and diet supplmented with 0.4% glutamine could significantly increase the average daily gain of minks (P<0.01), while significantly decreased the feed to gain ratio of minks (P<0.05). Serum glucose content and creatine kinase activity were not significantly influenced by adding glutamine in the diets (P>0.05), but diet supplmented with 0.4% and 0.6% glutamine could significantly increase the serum total protein content (P<0.05), and significantly decreased the serum urea nitrogen content (P<0.05). Diet supplmented with 0.2% and 0.4% glutamine could significantly improve the restraining hydroxyl free radical ability of minks (P<0.05), but there was no effect on the serum superoxide anion resistance ability (P>0.05). Diet supplmented with 0.4% and 0.6% glutamine could significantly decrease the serum malondialdehyde content (P<0.05), significantly increase the serum total antioxidant capacity (P<0.01), and significantly increase the serum glutathione peroxidase activity of minks (P<0.05). Taking into account of each index in this experiment, the suitable supplemental level of glutamine in diets of minks in summer is 0.4%.