To investigate the expressions of extracellular signal-regulated kinase (ERK) and p-ERK in benign and malignant prostate tissues, and whether it can be used as a marker for the prognosis of advanced prostate cancer (PCa).Using immunohistochemical Envision, we detected the expressions of ERK1/2 and p-ERK1/2 in 20 cases of benign prostatic hyperplasia (BPH) and 40 cases of advanced PCa and analyzed their correlation with PCa metastasis, Gleason score, PSA level, and prognosis.The expression of ERK1/2 was remarkably higher in the advanced PCa than in the BPH cases (82.5% vs 55%, P5 yr, and survival ≤ 5 yr groups were 61.9%, 89.5%, 57.9%, and 90.5%, respectively, with statistically significant differences among these groups (P<0.05).ERK1/2 and p-ERK1/2 proteins are highly expressed in advanced PCa and p-ERK1/2 is associated with the metastasis and prognosis of advanced PCa.