Early in this century, muscle relaxants for facilitating surgery and maintaining adequate airways were a dream of surgeons and anesthesiologists. Early in the 1950s curare and succinylcholine were developed; however, they had significant and undesirable cardiovascular effects. Pancuronium bromide decreased the incidence of histamine release and hypertension. Later it was discovered that tachycardia caused by pancuronium bromide could increase the incidence of ischemia. New muscle relaxants free of cardiovascular effects (vecuronium, doxacurium and pipecuronium) are discussed with the clinical implications of their onset and duration of action, as well as their interaction with calcium-channel and β-blockers. A technique for anesthetic management in cardiac surgery is also discussed.