Sixty patients, treated with postoperative radiation therapy following radical hysterectomy and pelvic lymphadenectomy for stage lb carcinoma of the uterine cervix between Jan. 1980 and Dec. 1984 at Department of Radiation Oncology, Yonsei University College of Medicine, were retrospectively analysed. The minimum follow-up period was 5 years. The indications for postoperative radiotherapy were positive pelvic lymph node (34 pts), a large tumor size more than 3 cm in longest diameter (18 pts), positive surgical margin (10 pts), deep stromal invasion (10 pts), and lymphatic permeation (9 pts). The overall 5-year survival rate was 81.8%. The univariate analysis of prognostic factors disclosed tumor size (< 3cm, ≥ 3cm) and the status of the surgical margin (positive, negative) as significant factors (tumor size; 88.1% vs 6.3%, surgical margin; 85.5% vs 60%, p < 0.05). Age (≤ 40, > 40 yrs) was marginally significant (90.2% vs 73.1%, p < 0.1). Multivariate analysis clarified two independent prognostic factors; tumor size (p = 0.010) and surgical margin (p = 0.004). Analysis of the tumor factors with the radiation dose disclosed a better survival rate for patients with a positive surgical margin who were given over 50 Gy than for those who were given below 50 Gy in patients (4/4, 100% vs 2/6, 33.4%; p = 0.06). Significant complications requiring surgical correction were not observed. In conclusion, it is believed that the status of the surgical margin and tumor size both have important prognostic significance, and that a radiation dose over 50 Gy is advisable for patients with a positive surgical margin.