Objective: It is reported that late-onset hypogonadism(LOH)is closely related to lower urinary tract symptoms(LUTS),and it is ameliorated by testosterone replacement treatment.And it is also reported that sleep duration and disturbances can affect testosterone level,muscle mass,and its function;however,there is no report indicating the efficacy of testosterone replacement on sleep related symptoms.We conducted a 12-week,placebo-controlled randomized control trial using newly developed 2.5%testosterone gel(TG)versus placebo gel(PG)in men with hypogonadism.Methods: We conducted a 12-week,double-blind,placebocontrolled clinical trial of TG versus PG in men with LOH symptoms.A total of 62 men ≥40 years old with LOH(total testosterone <450 ng/dL and total AMS scores ≥27)were randomized into TG or PG.For patients in TG group,7.5 mg testosterone with 2.5%TG was administered,and for those in PG group,gel without testosterone was administered once every morning for 12 weeks.Selfadministered questionnaires(IPSS,SHIM,EHS,Self-rating Depression Scale;SDS,State-Trait Anxiety Inventory;STAI,Athens Insomnia Scale;MS),blood sample,and physical measurement were completed at weeks 0 and 12.Results: One patient from TG group and 4 patients from PG group dropped-out during the study period.Total of 57 patients were analyzed(TG group;n=30,PG group;n=27).There was no significant difference between 2 groups in blood test,BMI,W/H ratio,grip strength,and questionnaires results at baseline.IPSS(10.7 to 8.8,P=0.020),STAI(state anxiety)(40.3 to 38.7,P=0.021),AIS(8.07 to 6.48,P=0.013)were significantly improved only in TG group.In IPSS,Q7(nocturnal frequency)was not significantly improved;however,Q4(urgency)was significandy improved in TG group.Conclusions: The current study showed that TG significantly improved STAI,IPSS and AIS compared with placebo.We conclude that hypogonadal patients with anxiety,storage symptom and sleep disturbance are good candidates for the testosterone replacement.