Forty-seven patients with chronic stable angina pectoris entered a thirteen-week open-label study with a transdermal therapeutic system of nitroglycerin in order to evaluate its clinical efficacy, safety, and patient acceptance. In 19 patients, a beta-blocker and in 17 patients a calcium-channel blocker were continued throughout the study period without alteration of their doses. The study consisted of a two-week run-in period and an eleven-week active drug period. Acute titration was done with nitroglycerin patches on the basis of weekly patient diaries on frequency of angina and sublingual nitroglycerin consumption. Overall, reductions in frequency of angina and in nitroglycerin consumption were statistically significant (p less than 0.05). Adverse reactions were common but tolerable. The reported side effects were headache in 32, skin rash in 18, dizziness in 10, palpitation and itching in 9 each, nausea in 7, flushing in 3, and vomiting in 1 patient. In conclusion, the present study demonstrates that individual dose titration with nitroglycerin patches for obtaining significant antianginal effect is essential. The present therapeutic system is convenient to use and well tolerated and had acceptable side effects in our study population.