Objective: The association between testosterone and nocturia has been the focus of several investigations,have shown sexual dimorphism.We supposed that the reason for the disparate findings between studies of male and female examing sex hormones in relation to nocturia include obstructive effect of benign prostate enlargement(BPE).We wonder about the relationship between testosterone and nocturia in men without BPE.To clarify the association between serum total testosterone(TT)and nocturia in male without enlarged prostate Methods: Among 1,029 patients were visited our clinic for screening of male health from January 2010 to March 2014,596 patients without BPE(prostate size ≤30 mL)were analysed.To evaluate the effect of serum testosterone on nocturia,multivariate analyses were performed including the covariates of age,IPSS score,IIEF score,BMI,PSA,prostate volume and maximal urine flow rate Results: Mean prostate volume was 21.70±4.34 mL.The multivariate regression analysis showed that Age,the total IPSS and testosterone levels were positively related to the occurrence of nocturia.However,no consistent association with the number of nocturia episodes was seen for testosterone after adjusting for relevant factors.Conclusions: A higher testosterone level was significantly associated with nocturia in our study.Therefore,in men without enlarged prostate,testosterone seems to have an opposing role in etiologies of nocturia.