An increased urine excretion has been reported in obstructive sleep apnea (OSA) patients, but it is not clear whether it results in an increased number of nocturnal micturitions. The present study was aimed at investigating the frequency of nocturnal micturitions in OSA patients using a standardized questionnaire prospectively given to 102 OSA patients and 86 healthy male subjects. The frequency of nocturnal micturitions was significantly greater in the OSA patients than in the healthy subjects (more than 70% of the OSA patients with an apnea+hypopnea index > 50 reported nocturnal micturitions more than twice a week versus less than 25% of the healthy subjects, p < 0.0001). The number of nocturnal micturitions was also greater in the OSA patients than in the healthy subjects. There was an effect of age on the frequency of nocturnal micturitions; however, when age-matched subsamples were considered, there was still a significant difference between OSA patients and healthy subjects. In a subgroup of 25 OSA patients reevaluated after at least 1 year of home treatment with nasal continuous positive airway pressure the reported frequency of nocturnal micturitions had significantly decreased (p < 0.001). These results suggest that investigations aimed at establishing a diagnosis of OSA should be part of the work-up of patients complaining of nocturnal pollakiuria.