The principal complaints of premenstrual tension noted a week prior to menses are nervousness, tension, swelling, headaches, depression, and breast soreness and turgidity; in severe form, these symptoms may progress to antisocial behavior and psychosexual abnormalities. Symptoms of the premenstrual tension syndrome may be due to latent edema, since many of the patients without apparent swelling were benefited by use of the diuretics alone. The usefulness of diuretics for control of premenstrual tension is well established. Chlorothiazide, in doses of 500 to 1,000 mg. administered daily for 7 to 10 days before menses, was given to 50 women with complaints referable to the premenstrual tension syndrome. Of the 50 patients, 33 complained of swelling. All of these patients showed an excellent response to chlorothiazide, with complete relief from their edema. Breast tenderness was a problem for eight patients, and, in each instance, the tenderness was relieved by chlorothiazide therapy. Headache was a presenting symptom in four patients, two of whom were relieved and two of whom noted no change while on chlorothiazide therapy.