In developing countries, the cost of antihypertensive medications is one of the principal limiting factors when trying to treat patients with high blood pressure. To determine the changes in cost (in US dollars) of these medications and in the percentage of the minimum wage needed to purchase them, two cost studies (1990 and 1996) done in Mexico were compared. The yearly cost of a treatment with hydrochlorothiazide was US $13.80 in 1990; in 1996 it was US $10.92. Both figures represent 1.1% of the minimum wage that was in effect at the time. Propranolol hydrochloride cost US $50.52 for a year's treatment in 1990, and US $66.12 for the same in 1996. These figures represented, respectively, 4.2% and 6.7% of the minimum wage of 1990 and 1996. The annual cost for nifedipine was US $176.76 in 1990 (14.7% of the minimum wage) and US $242.16 in 1996 (24.8% of the minimum wage). The yearly cost of enalapril was US $233.04 in 1990 and US $433.20 in 1996; these costs represented, respectively, 19.4% and 44.2% of the minimum wage. The comparison of these two cost studies (1990 and 1996) shows why Mexico's population is finding it more difficult to purchase antihypertensive medications. Higher costs and reduced purchasing power seem to be the two principal factors causing this. This is probably affecting the population's health, as it is more difficult to control high blood pressure without proper treatment.