Background: Liver resection is a standard treatment for resectable liver metastases (mets) from colorectal cancer. In patients (pts) with multiple or large liver mets, liver tumors may not be resected completely or recurrence after complete resection are frequently observed. Methods: This prospective single arm phase II trial assessed R0 liver resection rate after mFOLFOX6 + bevacizumab (BV) in pts with liver mets considered unsuitable for upfront resection. Pts with liver-only mets, those were larger than 5cm in diameter or more than 4 in number, were treated with 6 cycles of mFOLFOX6 + BV (without BV in the 6^th cycle). After chemotherapy, resectability of liver mets was assessed by CT or MRI. Secondary endpoints included liver resection rate, conversion rate from unresectable to resectable, safety of liver resection, recurrence rate, and survival. Results: Between May 2009 to October 2011, 46 pts were registered (one was excluded after registration due to ineligibility). Among the 19 pts with resectable mets at entry, 18, except one who refused the continuation of chemotherapy after the first cycle, underwent liver resection after 6 cycles of chemotherapy. In 16 of the 18 pts, R0 resection was performed. Among the 26 pts with unresectable mets at entry, 6 underwent liver resection and 4 had R0 resection. Overall R0 resection rate, liver resection rate and conversion rate were 44.4% (20/45), 53.3% (24/45) and 23.1% (6/26), respectively. The grade 3/4 adverse effects (AEs) by mFOLFOX6 + BV included fatigue (6.5%), stomatitis and nausea (2.2%), neutropenia (16.3%) and increase of serum total bilirubin (2.2%). As to BV related grade 3/4 AEs, hypertension (6.5%) and thromboembolism (2.2%) were observed. After liver resection, grade 3 wound infection, intra-abdominal abscess and delayed wound healing were complicated in two, in one and in one, respectively. Conclusions: In pts considered unsuitable for upfront resection of liver-only mets, mFOLFOX6 + BV was associated with high R0 resection rate, liver resection rate and conversion rate without severe toxicities and surgical complications. Updated results including survival will be presented. Clinical trial information: UMIN000002101.