BACKGROUND Rho-associated coiled-coil containing protein kinases 2 (ROCK2) is one of the best characterized targets for the small GTPase Rho. It has been reported that ROCK2 is critical for cancer cell migration and invasion. The objective of this study was to investigate the association of ROCK2 expression with clinicopathological features and overall survival of breast cancer patients. MATERIAL AND METHODS The expression of ROCK2 in breast cancer and paired adjacent normal tissues was detected and compared by immunohistochemical staining of tissue array. ROCK2 mRNA expression and clinicopathological information was extracted from the TCGA breast cancer dataset. The association of ROCK2 expression with the clinicopathological characteristics of patients with breast cancer was evaluated using univariate and multivariate Cox proportional hazards models. Overall survival was analyzed using the Kaplan-Meier method. RESULTS Immunohistochemistry showed that ROCK2 expression was significantly higher in tumor tissues than in paired adjacent normal tissues [immunoreactivity score (IRS): tumor, 5.25±2.10, n=40 vs. adjacent normal 3.83±1.06, n=40, P<0.01]. The IRS was correlated to breast cancer staging. Similarly, the mRNA level of ROCK2 was correlated to tumor stage. Notably, ROCK2 mRNA expression (hazard ratio [HR] 1.665 and 95% confidence interval [CI] 1.115-2.488, P=0.013) were also associated with overall survival in a multivariate analysis. CONCLUSIONS Upregulation of ROCK2 was associated with the progression of breast cancer. High expression of ROCK2 may predict poor overall survival rates for breast cancer patients.