Cardiac pacing may be useful in the management of supraventricular and ventricular tachycardias. Prophylactically, recurrent ectopic tachycardias may be prevented by atrial or ventricular pacing for a sustained period at a rate faster than the spontaneous rate, but slower than the rate of the tachycardia being suppressed. Moreover, the pacemaker permits the dosage of antiarrhythmic agents to be increased until the recurrent arrhythmias are completely controlled. Therapeutically, supraventricular tachycardias may be terminated by (1) overdrive suppression, (2) delivery of a single stimulus or two serial stimuli or repetitive stimulation at a rate slower than the tachycardia (competitive stimulation) and (3) orthorhythmic stimulation. Today, implantable units exist. Advantages and disadvantages as well as risks of pacing in patients with tachycardias, are discussed.