15103 Background: Chemoradiotherapy (CRT) after or before resection of high-risk rectal cancer (RC) improves overall survival (OS) and pelvic control. Thus, CRT is the standard adjuvant treatment in resected stage II/III RC. There are limited studies, if any, analyzing the outcome of RC patients with stage II/III who received adjuvant CRT after curative resection in Turkey. Therefore, we aimed to analyze the treatment outcome, and the prognostic significance of various parameters in these patients. Methods: 144 patients with stage II/III RC treated with adjuvant CRT since 1997 until present were analyzed retrospectively. Patients received 5-fluorouracil (375–425mg/m2/day × 5days) and calcium leucovorin (20mg/m2/day × 5days), q4weeks, two courses before and two courses after radiotherapy (RT). The 5- fluorouracil dose was reduced either to 225mg/m2/day given continuously as protracted short-term infusion during RT, or to 375–400 mg/m2/day on the first and last 4 days of RT. 45–50.4 Gy RT was given to the pelvic region. Patients were followed-up every 3 months for the first 2 years and every 6 months thereafter. Age, gender, TNM stage, and histological grade, lymphatic, vascular, and perineural invasion were analyzed as prognostic factors. Results: The median follow-up was 36 months starting from the operation date. Median age was 59 years. Forty- nine percent of the patients were node-negative. Lymphatic, vascular, and perineural invasion rate were 40%, 37.5%, and 26.3% respectively. Five-year disease-free and overall survival rates were 59.3% and 65.5%, respectively. Median overall and disease free-survival were not reached at the time of analysis. In univariate analysis T stage, node positivity, TNM stage, lymphatic invasion, and perineural invasion were independent prognostic factors for survival. In multivariate Cox regression analysis; only the presence of lymphatic invasion (p: 0.001), and vascular invasion (p: 0.01) were independent prognostic factors. Conclusion: The adjuvant treatment outcome in Turkish patients in our institution with stage II/III rectal cancer is similar to those reported in the Western studies. No significant financial relationships to disclose.