Urinary brain-derived neurotrophic factor (BDNF),an ubiquitous neurotrophin,was found to rise in patients with benign prostatic hyperplasia (BPH).We hypothesized that the urinary level of BDNF could be a potential biomarker for lower urinary tract symptoms (LUTS) in patients with BPH.Totally,76 patients with BPH-caused LUTS and 32 male control subjects without BPH were enrolled.Intational Prostate Symptom Score (IPSS) was applied to assess the symptom severity of LUTS.Urodynamic tests were performed for the diagnosis of underlying detrusor overactivity (DO) in the patients with BPH.Urine samples were collected from all subjects.Urinary BDNF levels were measured using enzyme-linked immunosorbent assays and normalized by urinary creatinine (Cr) levels.Seventy-six BPH patients were divided into moderate LUTS group (n=51,7＜IPSS ≤ 20) and severe LUTS group (n=25,IPSS＞20) according to the IPSS.Of the 76 BPH patients,DO was present in 34 (44.7％)according to the urodynamic test.The urinary BDNF/Cr levels were significantly higher in BPH patients with moderate LUTS (8.29±3.635,P＜0.0001) and severe LUTS (11.8±6.44,P＜0.0001) than normal controls (1.71±0.555).Patients with severe LUTS tended to have higher urinary BDNF/Cr levels than patients with moderate LUTS (11.8±6.44 vs.8.29±3.635,P=0.000).The conditions of BPH with LUTS correlated with elevated urinary BDNF levels,and urinary BDNF levels were even higher in BPH-DO patients.The results of this study have provided evidence to suggest that urinary BDNF level test could evaluate the severity of LUTS in BPH patients,and BDNF level can be used as a biarker for the diagnosis of DO in BPH patients.