Abstract. On the basis of a series of 112 patients with severe hypertension, treated in an outpatient clinic for an average period of 3.5 years, the most important visceral changes are described on the basis of retinal findings, electrocardiogram, heart volume and serum creatinine. The effect of treatment on these objective symptoms is correlated to the degree of reduction in blood pressure obtained. Reduction in the mean blood pressure to ≤ 133% of the normal for the age, produced a considerable regression of the retinal and cardiac changes caused by hypertension, whereas in about 90% of these patients the serum creatinine concentration did not increase during the period of treatment. A further reduction in blood pressure to ≤ 120% of normal produced corresponding but not better results. In patients with poorer regulation of blood pressure (blood pressure >133% of normal) the results, however, were considerably less favourable. The renal function at commencement of treatment was found to be of great importance for the prognosis.