SummaryIn 63 patients with uncomplicated essential hypertension plasma renin concentration and renal plasma flow were determined under metabolic ward conditions. Sodium intake was limited to 60 milliequi-valents per day. Patients remained under surveillance for an average period of 54 months.Major cardiovascular complications were observed in 11 subjects (myocardial infarction in 7, stroke in 4). Six of these had low renin hypertension. The claim that low renin hypertension represents a relatively protected condition could therefore not be supported. Nor were these subjects less vasocon-stricted than those with higher renin levels.