The main objectives of this study were to assess the use of irinotecan, 5-fluorouracil (5-FU), and leucovorin (FA) as neoadjuvant chemotherapy for patients with unresectable colorectal liver metastases and to determine the response rate and proportion of patients that could be down-staged to resectable tumors. Forty patients were treated with irinotecan (180 mg/m2 over 30 min) on d 1, FA (200 mg/m2 over 30 min) followed by 5-FU (400 mg/m2 bolus and continuous infusion of 600 mg/m2 over 22 h) on d 1 and 2 every 2 wk. The overall response rate was 55% (95% CI: 39.5-70.4%). The progression-free survival was 12.1 mo (95% CI: 11.4-14.8 mo). The median overall survival was 20 mo (95% CI: 17.7-26.6 mo). Four patients (10%) have undergone liver resection after a median of eight cycles. Those patients remained alive with a median follow up period of 33 mo. The principal grade 3-4 toxicity was neutropenia in 20 patients (50%). We conclude that the regimen of irinotecan/5-FU/FA was highly active in patients with colorectal cancer and liver metastases with limited toxicity. In a subgroup of patients with initial inoperable liver metastases, this regimen was able to down-stage the disease to an operable stage.