PROBLEM: The aim of this study was to contribute to the study of the pathogenesis and the treatment of recurrent spontaneous abortion (RSA) associated with immune alterations. METHOD OF STUDY: This is a prospective clinical trial with 11 patients with RSA associated with allo‐ and autoimmunity not receiving lymphocyte immunizations but only heparin and aspirin preconceptionally and through pregnancy. A concurrent group of 8 patients receiving a complete therapy (lymphocyte immunizations, heparin, and aspirin) but not receiving heparin and aspirin preconceptionally is also included in this report. RESULTS: The rate of pregnancy success in these patients was 90.9% (10/11), and the rate of success of the concurrent group was 75.0% (6/8). CONCLUSIONS: The results are in agreement with the working hypothesis regarding the possible final common mechanism in the pathogenesis of abortion associated with allo‐ and autoimmunity. The “single” therapy with heparin and aspirin was effective, less costly, and logistically simpler to provide than a complete therapy including lymphocyte immunizations.