The aim of this phase II study was to investigate the therapeutic value of second-line treatment with oxaliplatin, irinotecan (CPT-11) and mitomycin C (MMC) in patients with metastatic colorectal cancer pretreated with 5-fluorouracil (5-FU)-based chemotherapy. A total of 10 patients with metastatic colorectal cancer, all of whom had developed progressive disease from advanced or metastatic colorectal cancer while receiving or within 6 months after discontinuing first-line chemotherapy with 5-FU and leucovorin, were entered in this study. At the time of relapse, cytotoxic chemotherapy consisting of oxaliplatin 80 mg/m2 plus CPT-11 80 mg/m2 given i.v. on therapeutic day 1, and MMC 6 mg/ m2 given i.v. on day 15, respectively, was initiated. Treatment courses were repeated every 4 weeks for a total of six courses unless there was prior evidence of progressive disease. The overall response rate was 30% with three partial responses for all 10 assessable patients. Two additional patients (20%) had stable disease and five patients (50%) progressed. The median overall survival duration has not been reached yet and is longer than 7.1 months (range 2-23.5+) from the beginning of second-line therapy. Four patients are currently alive with progressive disease. The tolerance of second-line treatment was generally mild to moderate and easy to treat. Our data suggest that the combination of oxaliplatin, CPT-11 and MMC in patients with metastatic colorectal cancer pretreated with 5-FU-based chemotherapy is feasible and has substantial antitumor activity. Further evaluation of this regimen seems warranted.