There is evidence that depression may be associated with retention of sodium, and on recovery electrolyte changes return to normal (Shaw, 1966; Elithorn et al., 1966). In the premenstrual syndrome, psychiatric symptoms commonly occur, particularly depression; together with fluid retention. Thiazide diuretics, which cause excretion of water, potassium and sodium, are an effective form of treatment of the syndrome. In consequence, it would seem logical to assess the effects of a thiazide diuretic given to depressed patients.