The combination of radiation, fluorouracil, and oxaliplatin in locally advanced rectal cancer has been shown to be feasible in a phase I trial. The purpose of this phase II trial was to assess tolerance and efficacy of this regimen in a preoperative setting. Between May 2000 and October 2001, 40 operable patients were entered onto the study. Radiotherapy was delivered with a three-field technique to a dose of 50 Gy over 5 weeks with a concomitant boost approach. Two cycles of chemotherapy were given synchronously on weeks 1 and 5, with oxaliplatin 130 mg/m(2) on day 1 followed by 5-day continuous infusion of fluorouracil 350 mg/m(2) and L-folinic acid 100 mg/m(2). Surgery was planned 5 weeks later. All patients completed treatment without modification except one who experienced grade 3/4 toxicity. Grade 3 toxicity was seen in seven patients. Surgery was performed in all patients after a mean interval time of 5 weeks. An objective clinical response was seen in 30 patients (75%). Sphincter-saving surgery was possible in 26 patients. No postoperative deaths occurred. In four patients (10%), a reoperation was necessary (anastomotic fistula, n = 2; pelvic abscess, n = 2). In six cases the operative specimen was sterilized (15%), and in 12 cases (30%), only few residual cells were detected. Such a combined preoperative chemoradiotherapy and oxaliplatin-containing regimen is well tolerated with no increase in surgical toxicity. The good response rate observed warrants its use in further clinical trials.