Extended surgical staging (ESS) has been added to total hysterectomy and bilateral salpingo-oophorectomy (TAHBSO) in patients with clinical Stage I endometrial cancer in order to better define patterns of metastatic spread and the response to treatment. Adjuvant radiotherapy has a demonstrated efficacy in decreasing central recurrence in Stage I disease. The combined use of radical surgery and pelvic radiotherapy for cervical cancer patients results in an increased incidence of complications. This study compares major complication rates in Stage I endometrial cancer patients who underwent either TAHBSO with ESS or TAHBSO alone followed by adjuvant external beam radiotherapy (RT). Records of 52 patients with clinical stage I endometrial cancer were reviewed. Thirty-two patients underwent TAHBSO plus ESS and 20 patients had TAHBSO alone. All patients received postoperative, whole pelvis external radiotherapy. Four patients suffered complications potentially related to treatment which required rehospitalization, and all 4 were in the group which had undergone ESS. A comparison of complication rates between the ESS + RT group (4/37 or 10.8%) and TAHBSO + RT group (0/20) suggested a trend toward significance (P less than 0.10). Treatment protocols using extended surgical staging prior to adjuvant radiotherapy in Stage I endometrial cancer should examine complications potentially related to this combination, to further define treatment risks and benefits.