This is a retrospective analysis of 240 patients who had clinical Stage IB cancer of the cervix treated with radiation between 1969 and 1980. Of these, 186 patients were treated with a combination of external and intracavitary radiation therapy, and 54 patients received adjuvant postoperative radiation therapy. The minimum follow-up was 5 years. In the group who received only radiation therapy, the overall recurrence in 170 patients (excluding 16 patients found at laparotomy to have unresectable disease) was 17% (29 of 170); pelvic recurrence was 9% and distant metastases alone was 6%. In the group who received the adjuvant postoperative radiation therapy, 16 patients had a simple hysterectomy followed by vaginal ovoid and/or external pelvic irradiation for an unexpected Stage IB cancer of the cervix. Their overall recurrence was 37.5% (6 of 16). Pelvic recurrence was the most common treatment failure with a recurrence of 31%. Significant prognostic factors were depth of stromal invasion and status of surgical margins. Thirty-eight patients had a radical hysterectomy followed by postoperative radiation therapy because of positive pelvic lymph nodes and/or close surgical margins. In patients with positive pelvic lymph nodes, the overall recurrence was 39% (9 of 23); pelvic recurrence was 13%. Distant metastases, the most common treatment failure, was 26%. In seven patients with close surgical margins, five recurred in the pelvis. There was no distant metastases without pelvic failure. Five of eight patients with close paracervical margins recurred in the pelvis. All five of these patients were treated with vaginal ovoid irradiation alone. Whole pelvic irradiation plus vaginal ovoid irradiation is necessary in those with close paracervical margins. The vaginal ovoid irradiation alone should be limited to very selected patients with positive vaginal margins only.