Nocturia has a detrimental influence on life expectancy, health, and overall quality of life. Its prevalence is fairly equal in men and women and shows an age-related increase in both sexes. There are numerous medical conditions that are associated with increased nocturnal voiding, such as cardiac diseases, diabetes, obesity, edemas of different origins, and sleep apnea. On the basis of analyses of information collected from frequency-volume charts, the pathophysiological conditions underlying nocturia can be categorized as: nocturnal polyuria, a low nocturnal bladder capacity, or a combination of the two. Clinical conditions should be treated as appropriately as possible before more specific treatment of nocturia is considered. Clinical trials have specifically addressed the use of medications for treating nocturia through improvement of bladder capacity. Estrogen treatment has been shown to have a favorable influence on urological symptoms in general, but studies indicating a specific effect on nocturia are lacking.