The purpose of antihypertensive drug therapy is to lower the blood pressure safely and within the limits of tolerable side-effects. This attainment, however, requires a technique which is even more specialized than our present-day methods for controlling diabetes. The technique is based on the following principles. Technique of Antihypertensive Drug Therapy 1. Individual Differences. —Some patients will respond best to one type of antihypertensive agent, others to another. In addition, the dosage requirement may differ markedly from one patient to another. The duration of the blood pressure control also is variable, some patients requiring one or two doses per day, others three or four. Patients show marked differences in the incidence and severity of side-effects. There also is a difference in the ability of various patients to tolerate side-effects. Minor discomforts which will be treated as of no consequence by a stoical patient may assume disabling proportions in a more