1. Oral diazoxide was administered to a group of ninety-seven patients with renal failure and severe hypertension which had proved resistant to conventional drug treatment.
2. Hypertension was satisfactorily controlled in every case, and resistance to therapy did not occur.
3. Creatinine clearance showed a minor fall in the first week of treatment; however, by 3 months a significant improvement in renal function had occurred. This improvement was maintained at 6 months in the patients with primary hypertension and chronic pyelonephritis. In the chronic glomerulonephritic hypertensive patients, however, creatinine clearance was slightly lower at this stage.
4. Sodium retention was a conspicuous feature and required large doses of diuretics.
5. We suggest that vasodilatation leads to imbalance between filling pressure and capacity, so that volume receptors are stimulated. In addition, the decreased arteriolar resistance will lead to increased hydrostatic pressure in the capillary bed, and thus to increased fluid transudation.