Purpose: To assess the efficacy of the continuous positive airway pressure (CPAP) on nocturia in patients with obstructive sleep apnea (OSA). Methods: A literature review was performed to identify all published clinical trials of CPAP for the treatment of nocturia. The search included the following databases: MEDLINE, Embase, and the Cochrane Controlled Trials Register. The reference lists of the retrieved studies were also investigated. Results: Five publications involving a total of 307 patients were used in the analysis, which compared the number of incidents of nocturia before and after CPAP treatment. We found that patients with OSA and nocturia who were treated with CPAP had a significant decrease in the frequency of nocturia and the volume of urine associated with it. The mean number of nocturia incidents (standardized mean difference [SMD], -2.28; 95% confidence interval [CI], -2.42 to -2.15; P < 0.00001) and the associated urine volume (SMD, -183.12; 95% CI, -248.27 to -117.98; P < 0.00001) indicated that CPAP was effective. Besides, the Epworth Sleepiness Scale (SMD, -5.88; 95% CI, -6.56 to -5.21; P < 0.00001) and the CPAP apnea-hypopnea index (SMD, -31.57; 95% CI, -33.87 to -29.28; P < 0.00001) indicated that CPAP significantly improved the quality of sleep. Conclusions: This meta-analysis indicates that CPAP maybe an effective treatment for reducing nocturia associated with OSA and improving the quality of life of such patients.