The effects of dietary sodium chloride on the longevity, body weight, and food consumption in a normotensive strain (A/J) of mice was studied. Four groups of 50 mice each were fed diets containing 0.5 (control group), 1.5, 2.5, and 4.5% sodium chloride. The mean life span was 115.2 wk in the control group, and 115.5, 110,5, and 116.1 wk for groups 2, 3, and 4, with no significant differences from the control group. No differences were present in food consumption, but a graded weight loss was present after the 20th wk, which persisted throughout the experiment. No significant effect of salt loading was demonstrable on the extravascular fluid movement in either acute experiments or in the long-term dietary sodium chloride groups.