Background/Aim: Effect predictors of desmopressin for nocturia associated with nocturnal polyuria are understudied. Herein, we investigated the effects of desmopressin on sleep and patient quality of life. We defined cases in which administration of desmopressin led to hours of undisturbed sleep (HUS) >= 3 hours as "marked response cases" and examined predictive factors of desmopressin treatment response. Patients and Methods: Our study included 129 patients who were administered desmopressin 50 mu g for nocturia associated with nocturnal polyuria at our hospital. Efficacy and safety of desmopressin were examined using bladder diaries, International Prostate Symptom Score, Overactive Bladder Symptom Score, Athens Insomnia Scale, Patient Global Impression of Improvement (PGI-I) score, physical examinations, blood tests, and body composition analyzers, and the predictors of desmopressin efficacy were investigated. Results: Significant improvements in all endpoints were observed from the early stage onward after desmopressin treatment compared with before treatment. After treatment, HUS was significantly longer in patients with good PGI-I scores, which indicated patient satisfaction. Variation in nocturnal micturition frequency did not affect the improvement in patient satisfaction. Examination of cases defined as "marked response cases" showed that the mean night-time urine volume was an independent predictor of treatment