AIM: To evaluate the clinical efficacy of combination of active immunotherapy and allylestrenol in treatment of patients with unexplained recurrent spontaneous abortion (URSA) and to investigate a best therapeutic method in treatment of patients with URSA. METHODS: 435 patients with primary URSA were randomly assigned to three groups: 185 in combination medication group which was treated with active immunotherapy and allylestrenol, 152 in active immunotherapy group which was only treated with active immunotherapy, 98 in allylestrenol group which was only treated with allylestrenol. 96 secondary URSA in secondary URSA group were treated with active immunotherapy and allylestrenol. RESULTS: The successful pregnant rates of combination medication group, active immunotherapy group, allylestrenol group and secondary group were 92.05 %, 71.43 %, 31.51 % and 86.76 %, respectively. The successful pregnant rate in combination group were higher than that in the active immunotherapy group and the allylestrenol group (P 0.05 ). CONCLUSION: Combination of active immunotherapy and allylestrenol is better than other therapy method in treatment of patients with URSA, which is worth further widespread application in clinical practice.