ObjectiveTo assess the role of dietary sodium with or without chloride on the development of hypertension and left ventricular hypertrophy.Methods and results:Forty-nine male Sprague-Dawley rats with two-kidney, one clip hypertension were fed three different diets for 4 weeks after clipping: free access to sodium chloride, sodium citrate or sodium-free diet. Sham-operated rats were used as controls. The final conscious systolic arterial pressure was similar in all hypertensive groups, regardless of diet. A similar increase in left ventricular mass was observed in the rats on the sodium chloride and sodium citrate diets, whereas left ventricular hypertrophy was strikingly attenuated in the rats on the sodium-free diet.Conclusion:Dietary sodium restriction prevented the development of left ventricular hypertrophy without affecting consistently the final level of hypertension. Also, the anion associated with sodium had no influence on the level of arterial pressure and left ventricular mass when compared with rats maintained on sodium chloride. It is suggested that dietary sodium itself might be an important modulator of the left ventricular response to hypertension.