Idiopathic edema is usually orthostatic. It is most evident in the feet or abdomen after prolonged standing or sitting and in the fingers and eyelids after recumbency overnight. It occurs almost exclusively in post-pubertal women and is associated with discomfort in the areas of fluid accumulation (including symptoms of the carpal tunnel syndrome, nonarticular rheumatism, and headaches, sometimes with pseudotumor cerebri), and weight gain with excessive increments from morning to evening. The pathogenesis, diagnosis, and treatment of idiopathic edema are discussed.