The use of antihypertensive drugs (AHD) in the area n degrees 5 of the Institut Català de la Salut was evaluated for the period October 1986-December 1987. The unit of measure was the DDD (daily defined dose) per 1,000 population individuals per day. The overall use of AHD in 1987 was 49.31 DDDs/1,000 individuals/day; it was distributed among diuretics (53.5% of all AHD), beta-blockers (11.3%), and other AHD (35.2%). The most commonly prescribed drugs, by decreasing frequency order, were combinations of low ceiling diuretics with potassium sparing drugs, and of rauwolfia alkaloids with diuretics, followed by nifedipine, chlortalidone and furosemide. The interannual evaluation disclosed an increase of 18.6% in 1987 as compared with the preceding year, mostly at the expense of beta-blockers. On the other hand, there was a tendency to refrain from the use of fixed dose drug associations. This is a criterion of better use of antihypertensive therapy.