Liver resection is associated with prolonged survival in patients with colorectal liver metastases. At diagnosis, 15-20% of patients have resectable colorectal liver metastases whereas other patients have too advanced disease to enable surgical treatment and receive chemotherapy. In patients undergoing resection of colorectal liver metastases, disease relapse occurs in up to 70%. Therefore, a combined approach including preoperative or postoperative chemotherapy or both has been tested to improve outcome after surgery. In patients with unresectable colorectal liver metastases, chemotherapy is initially the sole treatment option. The considerable improvement of the efficacy of anticancer agents has contributed to increase the response rate in patients with advanced colorectal cancer. In case of major response to chemotherapy, surgery with curative intent can be offered to patients with initially unresectable liver metastases.