The diving response is now being applied clinically as a therapeutic measure to treat paroxysmal supraventricular tachycardia, and as an investigatory tool in dysfunction of the autonomic nervous system. This paper briefly reviews the current knowledge of the factors influencing the diving response in man, describes the procedure for optimising its clinical effectiveness, and reviews the literature concerning its relation to evoked and pre-existing arrhythmias. Present evidence indicates that the procedure is safe, however, pro tem it would be wise to use the procedure with resuscitation skills and appropriate support equipment nearby.