Summary Triamcinolone in doses of 40 to 50 mg. per square meter of body surface area per day appears to be an effective agent for the treatment of the idiopathic nephrotic syndrome. The status of the treated patients at the end of intensive steroid therapy and at the conclusion of a follow-up period is summarized in Table IV. Response to treatment is more consistent in patients whose proteinuria has been present for less than 4 months at the time treatment is instituted. In certain patients with proteinuria of greater duration, treatment may lead to a loss of edema and reduction in the degree of proteinuria without complete clearing of the urine of protein. The significance of the persistence of modest degrees of proteinuria in relation to the ultimate prognosis can be determined only by longer periods of observation. The urine of some patients has subsequently been cleared of protein with intermittent prophylactic therapy months after intensive steroid treatment has been completed. Periods of intensive steroid therapy beyond 28 days did not appear in these studies to lead to greater improvement in the degree of proteinuria. In the doses studied, the influence of triamcinolone on water and electrolyte excretion, arterial blood pressure, and body weight was not sufficient to interrupt the treatment plan. Prophylactic therapy in an interrupted fashion (3 consecutive days of each week) when coupled with social isolation and other anti-infection preventive measures appeared to be satisfactory in most patients in the prevention of recurrences.