Intensity modulated radiation therapy (IMRT) is receiving increasing attention in gynecologic malignancies. Numerous investigators have reported that IMRT planning reduces the volume of normal tissues irradiated compared to conventional techniques. Moreover, recent data have noted less acute and chronic toxicity in patients treated with IMRT. No data, however, have been published regarding tumor control in these patients. It thus remains unclear whether the highly conformal IMRT plans designed to spare normal tissues adversely impact tumor control. The purpose of this study is to present a preliminary analysis of our experience using adjuvant IMRT in endometrial cancer patients assessing tumor control. Between 2/00 and 3/03, 31 endometrial cancer patients received adjuvant intensity modulated pelvic RT (IM-PRT). Primary surgery consisted of TAH-BSO, peritoneal cytology and lymph node sampling. Seventeen (54%) had unfavorable histologies (5 serous, 1 clear cell, 11 carcinosarcoma). Twenty (64%) were FIGO stage I-II and eleven stage III-IV (pelvic only). Twelve patients (38%) also received intracavitary brachytherapy (20–30 Gy LDR or 21 Gy HDR) and five received chemotherapy (all carcinosarcomas). At simulation, an upper and lower body alpha cradle immobilization device was fabricated with the patient in the supine position. A contrast-enhanced planning CT scan was performed and a clinical target volume (CTV) was contoured consisting of the upper vagina, parametria and regional lymph nodes (common iliac, internal iliac, and external iliac lymph nodes). In two stage IIIC patients, the paraaortic lymph nodes were included. The CTV was then expanded by one centimeter producing a planning target volume (PTV). Normal tissues delineated included the small bowel, bladder, rectum and kidneys (if the paraaortics were included). Corvus Inverse Planning Software was used to generate IMRT plans consisting of 7–9 equally-spaced, 6 MV coplanar fields. The prescription dose was 45 Gy in 1.8 Gy fractions. Patients were followed with physical exams, cytology and CT scans. Late toxicity was graded using the RTOG/EORTC scale. All IMRT plans were highly conformal, with excellent PTV coverage and considerable sparing of the small bowel, bladder and rectum. At a median follow-up of 24 months (range, 5.4–44.6 months), five patients (16.1%) have recurred, for a 3-year actuarial disease-free survival (DFS) of 80.6%. The most significant factor correlated with relapse was histology. Patients with unfavorable histologies had a worse 3-year DFS (p = 0.04) than those with adenocarcinomas. All five patients who recurred failed in extra-pelvic sites. No patient recurred in the pelvis/vagina. Treatment was well tolerated with no patient developing grade 2 or greater chronic sequelae. Six patients (19%) developed grade 1 toxicity, predominantly mild diarrhea with select foods. One patient with a history of multiple abdominal surgeries developed an upper abdominal small bowel obstruction outside the irradiated field requiring surgery. Endometrial cancer patients treated with adjuvant IM-PRT have an excellent pelvic control and a low rate of toxicity. These preliminary results represent the first IMRT outcome series in endometrial cancer patients. While promising, larger patient numbers and longer follow-up are needed to confirm these results