This study examines the trends in drug treatment and costs of hypertension in a cohort of 1600 adult Aucklanders between 1982 and 1987. In 1987 prices the average daily cost of antihypertensive drug treatment per person increased from 42 cents to 74 cents over the five year period. The increase in cost seen in antihypertensive therapy in this cohort is explained by the introduction of new and more expensive drugs rather than by increases in the proportion of the population being treated for hypertension, daily dosage, number of antihypertensives per individual or in real prices of antihypertensives.