Screening for hypertension in the community leads to the identification of hypertensive people not previously detected, and those detected but inadequately treated or not treated at all. The aim of the present study was to assess the long-term efficacy of screening for blood pressure control in a general population. During 1981, 2139 parents of high school students were invited to our institute for a blood pressure measurement; 1533 persons (71.7%) attended the screening; 239 of them (15.6%) were found to be hypertensive (diastolic blood pressure s= 95 mmHg or already receiving antihypertensive treatment). Among the hypertensives, 42.3% did not know that they had high blood pressure, and only 7.5% had their blood pressure controlled by treatment. After being informed about the importance of lowering their blood pressure levels, all hypertensives were invited again to the institute for a further evaluation. Two hundred and two persons (84.5%) attended the re-examination. Of these, 154 (76.2%) were still hypertensive. Of the 202, 151 (74.7%) had contacted their physicians. The most common advice was to make further measurements of blood pressure over a period of time, followed by laboratory tests. The proportion of treated hypertensives rose from the initial 33.1 % to 53.9%, but in about half the patients normalization of blood pressure was not achieved. Physicians tended to treat only people with moderate to severe hypertension. The results of the present study, which are consistent with those observed in different socio-cultural conditions, suggest that one-time community screening for hypertension has limited efficacy in improving blood pressure control, unless it is integrated into a wider programme of health care.