The purpose of this study was to evaluate the efficacy and tolerance of a combination of irinotecan, oxaliplatin, and 5-fluorouracil (5-FU)/leucovorin in advanced colorectal cancer (ACC). Twenty-six consecutive patients with ACC and an Eastern Cooperative Oncology Group performance status of 0-2 were treated with a combination of oxaliplatin (120 mg/m2 intravenously [i.v.] for 2 hours) on day 1, irinotecan (250 mg/m2 i.v. for 90 minutes) on day 1, and 5-FU (2600 mg/m2 plus leucovorin 500 mg/m2 i.v. in a 24-hour infusion) on day 1 and 15, every 4 weeks. Five of the patients (19.2%) had shown previous chemoresistance. One hundred sixty-two cycles were administered (median, 6; range, 3-13 cycles). All patients were evaluated for toxicity; 23 were evaluable for response. According to intention-to-treat, the overall response rate was 69.2% (18 patients; 95% CI: 48.2%-85.7%), including 3 complete remissions (11.5%). Four additional patients (15.3%) had stable disease, and only 1 (3.8%) progressed. Major toxicities were neutropenia and diarrhea. Grade 3 neutropenia occurred in 9 patients (34.6%), and grade 4 occurred in 1 patient (3.8%). Grade 3 diarrhea occurred in 8 patients (30.7%) and grade 4 in 1 patient (3.8%). Other toxicities were mild. After a median follow-up of 15.5 months, the median progression-free survival was 14 months. Seventeen patients (65.4%) are still alive, and the median overall survival has not been reached yet. This combination of irinotecan, oxaliplatin, and 5-FU/leucovorin is fairly well tolerated and shows promising activity in ACC. This treatment merits further comparison with other combination regimens.