Objective To explore the effects and safeties of desmopressin on nocturia in elderly men.Methods We used random number table to divide patients into 2 groups.The patient in treatment group took desmopressin acetate tablets 0.2 mg orally and the patient in control group took tamsulosin hydmchloride sustained release capsule 0.2 mg orally before sleep for 4 weeks.The patient recorded 24 hours voiding diaries for 3 days and worked out mean number of nocturnal voids,hours of undisturbed sleep (HUS) before treatment and before subsequent visit weekly.Before treatment and 1 to 4 weeks after treatment,mean number of nocturnal voids,HUS,night quality of life (NQOL),quality of life (QOL),adverse event were recorded.Before treatment,1 week and 4 weeks after treatment,blood serum sodium was checked in treatment group.Results 42 men had been diagnosed with nocturia in outpatient department of investigator from December 2014 to March 2016,34 of them were recruited in our study and randomly enter the treatment group or control group.Each group consisted of 17 cases.There was no statistical difference in the baseline data between two groups (all P ＞ 0.05).The average ages of treatment group and the control group were (65.1 ± 11.2) and (63.9 ± 9.3) years old,the courses of disease were (3.0 ± 5.0) and (2.3 ± 2.6) years,respectively.Before treatment mean numbers of nocturnal voids were (3.8 ± 1.2) and (3.2 ± 1.4) times,HUS were (1.8 ± 1.7) and (1.8 ± 0.6) h,NQOL were (51.8 ± 13.8) and (41.2 ± 13.6),QOL were (4.0 ± 1.0) and (3.9 ± 0.9),respectively.Four weeks after treatment,mean numbers of nocturnal voids decreased to (1.6 ± 1.0) and (2.0 ± 0.9) times,HUS increased to (4.0 ± 0.7) and (2.6 ± 0.7) h,NQOL decreased to (20.9 ± 12.0) and (30.6 ± 12.4),QOL decreased to (1.4 ± 1.1) and (2.9 ± 1.0) in treatment group and control group,respectively.Every index of the two groups were statistically significant differences compared with that before treatment (P ＜ 0.05).There were statistically significant differences in the degree of improvement between treatment group and control group from 2 weeks to 4 weeks after treatment (P ＜ 0.05).Therefore,the degree of improvement of treatment group was superiored to the control group.Before treatment and both 1 week and 4 weeks after treatment,the blood serum sodium of patients in treatment group were (140.3 ± 3.9),(139.2 ± 4.3) and (140.6 ± 3.1) mmol/ L,respectively.Two patients of treatment group appeared dizzy during the follow-up period.In one of both,the symptom disappeared after the dose decreased from 0.2 mg to 0.1 mg per night.The symptom sustained and the dose was not changed in the other one.In treatment group,two other patients suffered from dyspepsia,one palpitation and one thirst.Those symptoms could be tolerated and the dose was not changed.In control group,2 patients suffered from thirst,one nasal congestion,one dizzy and one short of breath.All of those symptoms could be tolerated and the dose was not changed.There was not statistical differencebetween the occurrence rate of adverse events in the 2 groups (P =0.714).Conclusions Desmopressin can improve the symptoms of nocturia in elderly men,improve the quality of life of patients,and has goodsafety.