1. Sixteen rabbits received either a normal or a high cholesterol diet over an 80-day period.
2. Diastolic blood pressure remained unchanged in each group.
3. Progressive suppression of plasma renin activity and concentration without change in renin substrate occurred in animals receiving the high cholesterol diet.
4. Kinetic studies excluded the mediation of enzyme inhibitors in this response and made probable a true suppression of renin secretion.
5. Commonly recognized influences seemed not to account for the findings and the possibility is raised of a dependence of renin secretion upon serum cholesterol. The effect occurs at the level of serum cholesterol found in man.