Background/Aims: The aim of this study was to elucidate clinical indicators for the detection of advanced colorectal cancer (ACRC). Methods: This was a retrospective study conducted at a tertiary hospital. This study included 333 patients older than 85 years who underwent colonoscopy from April 2006 to May 2010. The detection rate of ACRC was assessed. Then, we analyzed the association between the detection of ACRC and various background factors including mean corpuscular volume (MCV). We also analyzed the cumulative overall survival of patients with detected ACRC. Results: ACRC was found in 37 patients, resulting in a detection rate of 15%. Multivariate logistic regression analysis revealed that a decreased MCV was an independent predictor for the detection of ACRC (OR 0.88, 95% CI 0.84–0.94), whereas symptoms such as abdominal pain, hematochezia, or anemia were not independent predictors. MCV was an independent predictor irrespective of the location of the tumor. The cumulative survival rates at 3 and 5 years after diagnosis were 78 and 58%, respectively, during a median observational period of 30.3 months. Conclusion: This study demonstrated the usefulness of MCV as an indicator of the necessity of colonoscopy for older patients.