The efficacy of immunotherapy using a streptococcal preparation, OK-432, was evaluated in each clinical stage of uterine cervical cancer. The 382 eligible patients were stratified by clinical stage and presence/absence of surgery. Within each stratum, patient's were randomly allocated to OK-432 treatment or to control treatment. OK-432 significantly inhibited recurrence in patients with stage II cervical cancer; the recurrence-free interval and survival time were remarkably prolonged in patients with stage II disease who underwent surgery. However, OK-432 did not significantly prolong these parameters in patients with stage III disease. Retrospective analyses revealed that in patients with or without lymph node metastases who underwent surgery, the recurrence-free interval and survival time were significantly prolonged by OK-432 treatment. These results indicate that OK-432 is an effective and useful postoperative immunotherapeutic agent for uterine cervical cancer.