1. Three groups of young patients with borderline hypertension were studied for a 12 months period. The first was on a free sodium diet while the second was on a low-salt diet. The third group of patients underwent acute salt loading.
2. After 12 months the group on free diet showed a significant increase of intralymphocytic sodium but no change in blood pressure was noted. Five patients who were re-checked after 24 months also had a significant increase in blood pressure.
3. Patients treated with a low-salt diet showed a significant decrease of both intralymphocytic sodium concentration and blood pressure.
4. After acute salt loading, borderline subjects with high intralymphocytic sodium showed a significant greater natriuresis whereas intralymphocytic sodium increased only in those subjects in whom it was initially normal.