Adrenergic-inhibiting antihypertensive drugs, most notably the beta-blockers and alpha-agonists, have been shown to influence a variety of central nervous system (CNS) functions. In some instances the use of these drugs has also been reported to lead to serious psychiatric complications. Despite the clinical significance of these effects and the potential threat to treatment adherence the underlying mechanisms are poorly understood. This article critically evaluates the existing research in six major areas: (a) depression, (b) lethargy/fatigue, (c) cognitive and perceptual-motor performance, (d) quantitative electroencephalogram (EEG) changes, (e) sleep, and (f) sexual function. In general, the evidence suggests that a pseudo-depressive state may be a relatively common side effect of treatment, and that associated changes in cognitive, affective, sleep, and sexual function may be frequently encountered.