(Introduction) Low-dose desmopressin is now available for the treatment of nocturia associated with nocturnal polyuria in men, and its usefulness in a dose-dependent manner has been reported. Since side effects such as hyponatremia have reported frequently, the initial dose has been set at 25 μg in many cases considering age and other factors. In the present study, we investigated the efficacy and safety of an initial dose of 50 μg in elderly patients. (Subjects and methods) At Chikugo city hospital, 45 patients were started on desmopressin at an initial dose of 50 μg for nocturia with nocturnal polyuria. Efficacy and safety after one and four weeks were evaluated based on bladder (micturition) diary. The investigated parameters included frequency of nocturnal urination, nocturnal polyuria index, time to first nocturnal void, first nocturnal urine volume, nocturnal urine volume, International Prostate Symptom Score (IPSS), Overactive Bladder Symptom Score (OABSS), and Athens Insomnia Scale. Physical examinations were also carried out, along with blood tests. (Results) The mean age of the patients was 78.3 years, which was higher than that reported in prior studies. After one week of treatment, there was a significant decrease in the frequency of nocturnal urination and nocturnal urine volume, as well as a prolongation of the time to first nocturnal void, improvement in nocturnal polyuria index, and improvement in IPSS, IPSS-QOL, OABSS, and Athens Insomnia Scale. In terms of safety, adverse events were observed in eight patients (17.8%), and hyponatremia was observed in seven patients (15.6%), which was comparable to the findings of prior reports. (Conclusion) Good therapeutic results were obtained in elderly patients at an initial desmopressin dose of 50 μg, indicating that the drug could be safely administered to elderly patients with regular follow-ups and appropriate withdrawal and dose reductions.