Recent data support the role of S100A10 in tumorigenesis. In this study, we evaluated the value of S100A10 positivity as a possible biomarker in colorectal cancer. We evaluated S100A10 positivity by immunohistochemistry in a large population of colorectal cancer patients (n = 882). The relationships between S100A10 positivity and clinicopathological features and clinical outcome were analyzed. There were 36 % (319/882) tumors positive for S100A10 in all colorectal cancer samples. In contrast, normal colorectal epithelium was negative for S100A10 among all 562 specimens of adjacent normal mucosa. S100A10 positivity was correlated with poor differentiation (p = 0.0012) and disease stage (p = 0.003). S100A10 positivity was significantly correlated with shortened specific [log-rank p < 0.001; multivariate hazard ratio (HR), 1.49; 95% confidence interval (CI), 1.09-2.04] and overall survival (log-rank p = 0.0012; multivariate HR, 1.34; 95% CI, 1.06-1.73). Knockdown of S100A10 by siRNA significantly reduced the proliferation, migration, and invasion capacity of colorectal cancer cell lines. Our results suggest a role for S100A10 as a prognostic marker and potential therapeutic target in colorectal cancer.