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The number of lymph nodes required for accurate staging is a critical component in colorectal cancer. Current guidelines demand at least 12 lymph nodes to be retrieved. This study was designed to determine the factors that influence the number of harvested lymph nodes (> 12) in resective R0 CRC in a single institution.Between July 2005 and April 2010, data on patients who underwent surgery for CRC were analyzed retrospectively (340). Data for a total of 244 R0-surgery patients were collected and all the tumor-bearing specimens were fixed with node identification performed. Several possible factors that influence 12 or more harvested lymph nodes were investigated and classified into four aspects: operating surgeon, examining pathologist, patient (age, sex, and body mass index), and disease (tumor localization, tumor cell differentiation, tumor stage, type of resection).A total of 157 patients (64.3%) with 12 or more harvested lymph nodes and 87 patients (35.7%) with < 12 lymph nodes were analyzed. The results demonstrate that tumor localization, depth of tumor invasion according to Dukes stage and grading were independent influencing factors of 12 or more harvested lymph nodes. Neither the operating surgeon nor the examining pathologist had significant influence on the number of harvested lymph nodes.The number of harvested lymph nodes was highly variable in patients who underwent resection of R0 CRC. Therefore, disease itself is the most important factor influencing the number of harvested lymph nodes.