Background: XELOX plus bevacizumab (Bev) is one of the standard therapies for metastatic colorectal cancer (mCRC). However there was no clinical practice date in Japan. This study was designed to evaluate the efficacy and safety of XELOX plus Bev in the clinical practice in Japanese mCRC patients (pts) including the elderly. Methods: The study design was multicenter, single-arm, open-label prospective study. The major inclusion criteria were previously untreated mCRC; presence of measurable lesions; age 20 years; ECOG performance status (PS) 0–2; and adequate organ function. Pts received Bev 7.5 mg/kg d1 and XELOX (oxaliplatin 130 mg/m² d1 plus capecitabine 1,000 mg/m² bid d1-14) q3w. This schedule was repeated until unacceptable toxicity or disease progression occurred. The primary endpoint was RECIST-confirmed objective response rate (ORR). A sample size of 41 was planned for a threshold ORR of 30% and expected value of 50%, with one-sided alpha of 0.05 and beta of approximately 0.2. Results: Of the 47 pts (male/female, 29/18; median age, 66 years (range 38-81); PS 0/1/2, 40/5/2) enrolled from May 2010 to Mar 2011. One patient did not fulfill the eligibility criteria. 46 pts were assessed for response; CR 1 pts, PR 23 pts, SD 15 pts, PD 2 pts, and NE 5 pts. The confirmed ORR was 52.2% (90% CI, 39.2-65.0%). The response rate across all time points without confirmation was 67.4% (95% CI, 52.0-80.5%). Median PFS and OS have not yet been reached. The most common grade 3/4 adverse events were anorexia 12.8%, neutropenia 10.6%, fatigue 8.5%, hypertension 4.3%, thrombocytopenia 4.3%, hand-foot syndrome 2.1% and bleeding 2.1%. Grade 3/4 peripheral neuropathy did not occur. Conclusions: First-line treatment of XELOX + Bev showed a promising response rate and an acceptable tolerability profile in the clinical practice in Japanese mCRC pts including the elderly. Clinical trial information: UMIN000003915.