Ｏｂｊｅｃｔｉｖｅ　To investigate the effect of intraperitoneal injection (i.p.) of yohimbine, an α2-receptor antagonist, on the analgesia effect of dezocine in rats.　Methods　Eighty male SD rats were randomly divided into 8 groups (n=10): group A1, group B1, group C1, group D1, group A2, group B2, group C2, and group D2. Plantar injection of complete freund′s adjuvant (CFA) was used to induce chronic inflammatory pain in group A1, group B1, group C1, and groupD1. Saline, dezocine (2.5 mg/kg), dezocine (2.5 mg/kg) plus yohimbine (2.5 mg/kg), and yohimbine (2.5 mg/kg) were injected intraperitoneally at 3 d after establishment of disease models, respectively. Thermal withdrawal latency (TWL) and paw withdrawal threshold (PWT) were measured at 30 min after the injection. Chronic constriction injury (CCI) of sciatic nerve was used to induce neuropathic pain in group A2, group B2, group C2, and group D2. Saline, dezocine (2.5 mg/kg), dezocine (2.5 mg/kg) plus yohimbine (2.5 mg/kg), and yohimbine (2.5 mg/kg) were injected intraperitoneally at 7 d after establishment of disease models, respectively. TWL and PWT were measured at 30 min after the injection.　Results　TWL and PWT were significantly increased in group B1 [(16.7±3.2) s, (12.1±2.0) g] and group C1 [(12.3±3.5) s, (7.8±3.3) g] compared with group A1 [ (8.3±2.0) s, (5.0±1.6) g ] (P<0.05). However, no significant difference was examined between group A1 and group D1 (P>0.05). TWL and PWT were significantly reduced in group C1 compared with group B1(P<0.05). TWL and PWT were significantly increased in group B2 [(11.3±3.0) s, (11.4±3.3) g] and group C2 [(8.7±1.6) s, (6.4±0.7) g] compared with group A2 [(6.2±1.9) s, (4.6±1.5) g] (P<0.05). However, no significant difference was examined between group A2 and group D2 (P>0.05)TWL and PWT were significantly reduced in group C2 compared with group B2(P<0.05).　Conclusions　Intraperitoneal injection of yohimbine reduced the analgesia effect of dezocine under the chronic inflammatory and neuropathic pain conditions in rats.