To investigate the efficiency of immunocastration by using gonadotropin releasing hormone analogue (GnRH-A) in rabbits,GnRH-A was combined with bovine serum albumin (BSA) as well as incomplete Freund's adjuvant to make antigen emulsion.A total of 30 rabbits (Oryctolagus cuniculus) were injected with 1.0 ml(100 μg/ml)GnRH-A antigen emulsion at 2 to 3 spots in two groups,EG-Ⅰand EG-Ⅱ groups.The EG-Ⅱgroup was reinjected with the same dosage after 3 weeks.The testis length and weight as well as body weight of the immunized rabbits were measured,and GnRH antibody titer and testosterone concentration were detected by ELISA.There was a significant difference in the testis length between EG-Ⅰand EG-Ⅱ groups(P<0.01); antibody level of EG-Ⅱgroup was obviously higher than that of EG-Ⅰgroup; serum testosterone concentration in both EG-Ⅰgroup and EG-Ⅱgroups differed remarkably from 7 to 16 weeks when compared with the control (P<0.05 ); testosterone concentration in EG-Ⅱgroup was lower than that in control group (CG) at 102 d(P<0.01),and testosterone concentration in EG-Ⅰgroup was also lower at 28 d(P<0.05) after the injecting GnRH-A antigen.Body weight and average daily body weight gain in EG-Ⅱ group were significantly higher than in EG-Ⅰand CG groups (P<0.05).In summary,the testis development,serum GnRH antibody titer and testosterone level in experimental rabbits change obviously after active immunization with GnRH-A and an additional injection strengthenes castration effects.