During the last 20 years antihypertensive treatment has given excellent results in terms of prevention of cardiovascular complications. However these results, for some reasons, are less satisfactory than those theoretically possible. The problems we need to solve are many and all contribute to reduce the efficacy of therapy. First of all it is necessary to make a correct diagnosis of hypertension to avoid treating normotensive subjects. The use of continuous ambulatory blood pressure monitoring in some cases can be useful to clarify these situations and also to better evaluate the efficacy of therapeutic regimens. In the vast majority of cases, however, the traditional blood pressure recordings, if correctly performed, can give satisfactory and sufficient information. After a correct diagnosis is made the physician must start with the patient an open-minded cooperation based on confidence. He must clearly explain the goals and the methods of therapy and encourage, instead of frighten, the patient. The next step is the choice of the kind of treatment in which many factors must be kept in mind and in which the physician must have a deep knowledge of the patient and of the drugs. Treatment has a high probability rate of a good patient's compliance only if it does not cause adverse reactions and if the therapeutic scheme is simple. Studies on compliance have shown that it is possible to identify those patients at risk of low compliance even before the beginning of therapy and it has been shown that adverse reactions especially if the patient has not been informed by the doctor, can cause a dramatic fall in compliance.(ABSTRACT TRUNCATED AT 250 WORDS)