Four hundred patients from eight health centres were recruited for this two-year study on the possibility of replacing antihypertensive drugs by non-pharmacological therapy. This consisted of monthly check-ups and blood pressure measurements at home by the patients plus advice about changes of lifestyle--salt restriction, weight reduction, physical activity, and reduction of alcohol and tobacco. The non-pharmacological treatment was effective and 44% had discontinued drugs after two years without any increase in diastolic blood pressure. Twenty-five per cent reduced their weight by 4% or more. There were no changes in sodium or potassium output. Thirty-five per cent increased their physical activity and 20% decreased it. When the results for each health centre were compared, striking differences in hypertensive characteristics of patients and the outcome of antihypertensive drug treatment were found. In one health centre 69% of patients were not taking drugs after two years. In some health centres the non-pharmacological treatment was quite successful, but in others the attempt failed. A prerequisite for successful use of pharmacological treatment is that the problem of non-compliance should be solved.