Regular biennial health screenings of the Busselton population between 1966-75 resulted in the recognition of individuals with hypertension and a progressive increase in the adequacy of control of blood pressure in those on treatment. Between 1973-77 observed mortality from strokes (CVA) in males 50 yrs and over declined significantly as might be expected from the smaller numbers at risk from raised blood pressure. No favourable trends occurred in the incidence of CVA in women despite better control of hypertension. In the population as a whole, CVA mortality in untreated or inadequately controlled hypertensives was significantly greater than in normo-tensives or adequately controlled hypertensives.