A health examination survey comprising 2 322 men born in 1920-24 was carried out in 1970-73 at the University Hospital, Uppsala. Untreated subjects with a diastolic BP greater than or equal to 105 mmHg and those already on treatment for hypertension were considered hypertensives. If a BP elevation was verified at a second screening and the patient had no established contact with a physician, he was offered treatment. Thus, 83 men have been followed up for at least 6 years. The overall reduction in SBP after 6 years was 29.0 mmHg and in DBP 19.6 mmHg. Six men have died, four of them from myocardial infarction, five have dropped out for other reasons. The percentage of non-responders (DBP greater than or equal to 105 mmHg) 1, 2, 3, 4 and 5 years +/- 3 months after the start of treatment was high, about 20% on the average. On the other hand, when the mean BP for the non-responders at all visits to the hypertension clinic was compared with their pretreatment value, a reduction of 29.3 mmHg in SBP and 17.0 mmHg in DBP was achieved. The results with regard to compliance and BP reduction are encouraging and would seem to justify more widespread screening and treatment.