Ninety-one middle-aged men and women with untreated mild hypertension were allocated to a nopharmacological treatment group or to a control group. Members of the treatment group were instructed to reduce daily sodium intake to less than 70 mmol, to reduce the intake of saturated fat, to lose weight if necessary and to perform regular physical exercise and relaxation training. Adherence to and effects of the programme on blood pressure and serum lipids were monitored for 12 months. In the treatment group, daily sodium excretion decreased to and remained at 50% of its original level (P less than 0.001), and there was a significant reduction in saturated fat intake. The average weight reduction was modest. Adherence to physical exercise and relaxation training regimens was poor. The net decreases (difference in changes between treatment and control group) in blood pressure were greatest during the first 3 months: in men the decrease in systolic blood pressure was 11.3 mmHg (P less than 0.001) and in diastolic blood pressure 8.3 mmHg (P less than 0.001); in women the decrease in systolic blood pressure was 10.8 mmHg (P less than 0.01) and in diastolic blood pressure 6.4 mmHg (P less than 0.01). However, this decrease diminished during the last 3 months to approximately one half owing to blood pressure reduction in controls. Low density lipoprotein cholesterol levels decreased significantly in treated men and women.