Calcium channel blockers constitute a very important group of drugs that are commonly used in the treatment of cardiovascular and cerebrovascular disorders. Current indications for these medications include hypertension, angina, supraventricular arrhythmias, and prevention of coronary and cerebral vasospasm. Although calcium channel blockers originally held great promise in the treatment of myocardial and cerebral ischemia, clinical results have been discouraging. An understanding of the basic physiological mechanisms of actions for these drugs is important for the practising clinician and may explain the disappointing results for the treatment of ischemia to date. This paper is a narrative review, from a clinician's viewpoint, of the structure and role of calcium channels in cardiac and cerebrovascular tissues, as well as a review of the in vitro and clinical results of calcium channel blockade in myocardial and cerebral ischemia.