PURPOSE: Complete resection of liver metastases of colorectal origin is the only potentially curative treatment. In order to decrease recurrences, the use of adjuvant systemic chemotherapy after liver resection is controversial because no randomized study demonstrated its benefit. PATIENTS AND METHODS: In a multicenter trial, we randomly assigned 173 patients with completely resected (R0) hepatic metastases from colorectal cancer to surgery alone and observation (87 patients) or to surgery followed by 6 months of systemic adjuvant chemotherapy with a fluorouracil and folinic acid monthly regimen (86 patients). The main outcome criterion was disease-free survival. Secondary outcome measures were overall survival and treatment-related toxicity. RESULTS: The intention-to-treat analysis was based on 171 patients, after a median follow-up of 87 months (SE = 5.8). The 5-year disease-free survival rate, after adjustment for major prognostic factors, was 33.5% for patients in the chemotherapy group and 26.7% for patients in the control group (Cox multivariate analysis: odds ratio for recurrence or death = 0.66; 95% CI, 0.46 to 0.96; P = .028). With regard to secondary outcome measures, a trend towards increased overall survival was observed but did not reach statistical significance (5-year overall survival: chemotherapy group, 51.1% v control group, 41.1%; odds ratio for death, 0.73; 95% CI, 0.48 to 1.10; P = .13). CONCLUSION: Despite a suboptimal regimen, which was the standard at the beginning of the study, adjuvant intravenous systemic chemotherapy provided a significant disease-free survival benefit for patients with resected liver metastases from colorectal cancer.