The incidence of resistant hypertension remains to be clarified. In this article, three categories of resistance are distinguished: resistant patient, resistant clinician and refractory hypertension. Inadequate compliance, which in case of antihypertensive treatment means taking fewer doses of medications than prescribed, remains a significant cause of poor blood pressure control. Among most frequent physician-related causes of resistant hypertension, there are measurement errors, pseudohypertension, white coat hypertension and therapy errors. Careful elimination of patient- and physician-related reasons of inadequate blood pressure control should lead to the diagnosis of truly resistant hypertension. One of the causes of refractory hypertension may be concomitant use of other medications that are known to reduce antihypertensive effect of main drugs. Resistance may be associated with increased intravascular volume or fluid overload or with sympathetic activation. Modifiable contributing factors responsible for resistant hypertension include obesity often coexisting with insulin resistance and metabolic syndrome as well as excessive alcohol use and cigarette smoking. Another potential cause of refractory hypertension is the presence of secondary hypertension. Certain therapeutic modifications are essential in resistant hypertension.