This study was conducted to determine the amount of nitroglycerin released from transdermal nitroglycerin patches of four different sizes: 3.3 cm2, 6.7 cm2, 13.3 cm2, and 20 cm2. Thirty healthy men received a single 24-hour application of each patch size according to a randomized, open-label, four-period crossover design. A 24-hour interval separated each treatment period. The total amount of nitroglycerin released by the four patches was proportional to size. All four patch sizes released nitroglycerin at a comparable rate. The mean overall 24-hour release rate of 0.76 mg/cm2 was similar to the release rate of 0.75 mg/cm2/24 hr observed in a previous study. Adverse experiences common to nitroglycerin administration were reported for all patch sizes, with headache, light-headedness, and nausea reported most frequently.