Lymphocyte-to-monocyte ratio (LMR), one of the systemic inflammatory biomarkers, is reported to be involved in cancer detection and prognosis. Here, we developed a prostate cancer (PCa) risk nomogram including LMR for initial prostate biopsy, and internal and external validation were furtherly conducted. A prediction model was developed on a training set of 820 patients. Significant risk factors with P 4% and <99%. The nomogram predicting PCa risk in patients with PSA 4-10 ng/ml also displayed good calibration and discrimination performance (C-index: 0.734, 95% CI: 0.708-0.760). This nomogram incorporating age, PSA, DRE, abnormal imaging signals, PSAD and LMR could be used to facilitate individual PCa risk prediction in initial prostate biopsy. Funding Statement: This study was partly funded by the National Natural Science Foundation of China (Grant No. NSFC 81502195) and Medicine and Health Science Technology Development Project of Shandong Province (No. 2016WS0258). Declaration of Interests: The authors declare no competing financial interests. Ethics Approval Statement: This study was approved by the Institutional Review Board of The Affiliated Hospital of Qingdao University (AHQDU) and Fudan University Shanghai Cancer Center (FUSCC). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Written informed consent was obtained from all subjects prior to participation.