1. Portacaval anastomosis was carried out in ten rats fed on a 60% sucrose/5% lard diet, which induced moderate hypertriglyceridaemia, mild hypercholesterolaemia and normotension.
2. Plasma triglyceride was decreased to 45% of concentrations observed in ten pair-weighed control rats.
3. Plasma cholesterol concentrations were reduced to 58%, renin substrate to 70% and aortic blood pressure to 80% of control values by portacaval shunt surgery.
4. Individual blood pressures were directly related to plasma renin substrate concentrations.