Objective To investigate effects of acupuncture combined with Fluoxetine on behavior and regulatory T cell （Treg） proportion in mice of chronic depression. Methods Sixty Balb/c mice were randomly divided into a normal control group （group A, n=10） and depression model group （n=50）. Fifty Balb/c mice were irritated with a variety of chronic unpredictable moderate stress stimulations for 21 days to prepare the mouse depression model. After successfully modeling, 50 depression model mice were randomly divided into 5 groups, a model group （group B）, a fluoxetine group （group C）, an acupuncture group （group D） and a combined acupuncture and medicine group （group E） and a sham acupuncture group （group F）, 10 mice in each group. The mice in the group C were intragastrically administrated with Fluoxetine once （20 mg/kg）; for the group D, electroacupuncture （EA） was given at ＂Baihui＂ （百会 GV 20） and ＂Shenting＂ （神庭 GV 24） and for the group F, EA was given at non-acupoint of the buttock for 2 min; for the group E, acupuncture combined with Fluoxetine was used with the same acupoints, methods and medicine as those in the group D and C. The treatment was given once each day, for 21 consecutive days. After treatment the open-field behavior （retention period at the central square, horizontal movement,vertical movement, etc.）, sucrose preferences, body mass, food intake and other behaviors were observed, and the proportion of regulatory T cells （CD4^＋ CD2^＋5 Foxp3^＋ Treg cells） was analyzed with flow cytometry. Results Compared with the normal control group, the open-field behavior showed depression-like changes, and humoral consumption, sucrose preferences, body mass and food intake significantly decreased in the mice of the depression model group. After treatment, compared with the group B, the behaviors of the mice in the group E, C and D were improved in varying degrees; compared with other groups, the group E had more obvious effect on vertical mo
