Radical hysterectomy for uterine cervical cancer was performed on 469 patients without metastasis in either the parametrium (P) or pelvic node (N). In 225 of the patients, the tumor had invaded deeply, with the remaining non-invaded myometrium being less than 5 mm deep. In 54 of the patients, the tumor had invaded the vagina. These two sets of cases (postoperative advanced Ib and IIa) were the subjects of the present examination. Eighty-three of the 225 patients were given postoperative irradiation, and 142 were not. The 5-year survival rates were 84% (70/83) in patients with irradiation and 92% (131/142) in those without irradiation (p less than 0.10). Eight patients with irradiation died of causes which might be attributable to the irradiation. The rates of recurrence were similar in both groups (8.4%, 7/83 vs 9.2%, 3/142). However, there was a significant difference (p less than 0.025) between these two groups (1.2%, 1/83 vs 2.8%, 4/142) in the recurrence rate when only the areas of irradiation were considered. In the 54 patients with IIa cancer, the 5-year survival rates and the rates of recurrence were not significantly different for those patients with irradiation from those without irradiation. Therefore, these results indicate that postoperative irradiation may not be essential for P(-)N(-) patients.