Irritant contact dermatitis caused by occupational contact with nitroglycerin has been known since the end of the last century. Nitroglycerin is an allergen, and the transdermal drug delivery systems for nitroglycerin recently used to treat angina pectoris have sensitized. 4 patients with allergic contact dermatitis caused by nitroglycerin from explosives are described, and 1 patient who was sensitized by transdermal nitroplaster. On patch testing, dynamite and/or the explosive components nitroglycerin, ethylene glycol dinitrate and dinitrotoluene gave allergic reactions. The following concentrations and vehicles are suggested for patch testing: nitroglycerin 0.5-2% pet., dinitrotoluene and ethylene glycol dinitrate 0.1-0.5% pet. Persons exposed to nitroglycerin at work should try to avoid skin contact by using protective gloves. It is advisable that those who have become allergic to nitroglycerin should wear disposable protective gloves when handling explosives.