Background: The identification of new prognostic markers for prostate cancer is highly warranted, since it is difficult to identify patients requiring curative treatment. Data from both experimental models and clinical samples have identified important functions of PDGFRb on pericytes and fibroblasts in the tumor stroma. Methodology/Principal Findings: In this study the prognostic significance of PDGFRb in prostate cancer stroma, and in matched non-malignant tissue, was evaluated with immunohistochemistry. PDGFRb expression was analyzed in normal and tumor stroma from more than 300 prostate cancer patients. High PDGFRb expression in tumor stroma was associated with large tumor size, advanced stage, high Gleason score and high vessel density. Perivascular PDGFRb staining in tumors was also correlated with high Gleason score. Correlations were also observed between PDGFRb status in tumor stroma and nonmalignant stroma. Similarly, high PDGFRb expression in adjacent non-malignant tissue stroma correlated with large tumor size, advanced stage, high Gleason score and proliferation in non-malignant epithelium. Interestingly, high levels of PDGFRb in the stroma of tumor and non-malignant tissue were associated with shorter cancer specific survival in prostate cancer patients. Conclusions/Significance: The study revealed a number of novel associations between stromal PDGFRb expression i
