Abstract: Objective: To discuss the experimental evaluation and clinical significance of human leukoyte antigen(HLA) immunization therapy of habitual abortion on unknown causes.Methods: Thirty-six patients who had abortion over 3 times and their husbands were detected of the HLA by serum assay.Results: Twenty-nine of the 36 cases treated with lymphocyte therapy were successful in pregnancy,the success rate being 87.5%.Conclusions: Intradermic injection of the husband's lymphocyte is effective in treatment of habitual abortion of unknown causes and the therapy is simple and safe in operation.It is worth popularizing.