KRAS mutation occurs in 30% to 50% of colorectal cancers (CRCs) and has been suggested to be associated with proliferation and decreased apoptosis. In this study, we analyzed KRAS in 198 CRCs and compared the clinicopathologic variables between KRAS-mutated and wild-type CRCs. Also, a subset of 90 and 66 CRCs from this cohort underwent microsatellite instability testing and histomorphologic evaluation, and the frequency of microsatellite instability-high (MSI-H) and histomorphologic variables were compared between KRAS-mutated and wild-type CRCs. Clinicopathologic features (age, sex, and tumor site, depth, size, grade, and metastasis) were not different between KRAS-mutated and wild-type CRCs. Compared with wild-type KRAS CRCs, KRAS-mutated CRCs had a lower frequency of MSI-H (15% vs 42%; P = .015), a higher chance of having brisk mitosis (77% vs 43%, P = .022) and apoptosis (77% vs 28%; P = .00012), and a greater mean of mitotic figures (P = .0002) and apoptotic cells (P = .0008). KRAS mutation was associated with higher tumor cell turnover.