Nitroglycerin is a vasodilating agent by virtue of its actions on vascular smooth muscle fibers. It may be administered intravenously (using either 5 p. cent dextrose, or propylene-glycol solvant), sublingually, orally or by topical administration. It is rapidly metabolized, principally by liver. Its is not toxic. The vasodilatation that is produced is both arterial and venous and is dose-related in dog (1 microgram to 100 micrograms/kg/min). However, resistance and tachphylaxis may occur. Its principal use is for angor treatment, but it has been used for the treatment of arteriopathy of the lower limbs, biliar hypertony and arterial hypertension. It has been recently administered for the treatment of acute phase of myocardial infarction and during pre, per- and post-operative periods in cardiac surgery, neurosurgery and hip surgery, as myocardial protector or anti-hypertensive agent or hypotensive agent. The absence of toxicity and the rapid reversibility of its cardio-vascular effects which are similar to the effects of sodium nitroprusside are important reasons for its use in anesthesia and cardiac intensive care.