Hexacarbacholine is a long-acting muscle-relaxant drug that had been used extensively in Europe in surgical anesthesia, but had had considerably less clinical usage in US. There is no precise agreement concerning the mode of action of hexacarbacholine at the myoneural junction. Therapeutic doses of the drug do not appear to influence the cardiovascular system, cardiac activity, or blood pressure, although large doses do cause slight and transient increases in blood pressure in laboratory animals. The intraocular tension in man is increased temporarily following the administration of hexacarbacholine. Since hexacarbacholine is a cumulative drug, repeated administrations should be avoided. It may cause cardiac arrest due to a hyperkalaemia.