The stability of intravenous nitroglycerin solutions prepared from either sublingual tablets or a 10% nitroglycerin-lactose adsorbate (powder) was examined under various conditions. Nitroglycerin concentration was measured by high-pressure liquid chromatography. Nitroglycerin stock solutions (0.8-1.0 mg/ml) prepared from tablets or powder in either 0.9% saline were stored upright in refrigerated multidose vials for 6 months without a significant decrease in concentration. Storage of the solutions at room temperature resulted in a 20% loss after 3 months. Intravenous nitroglycerin solutions (0.2 mg/ml) prepared from tablets or powder in 0.9% saline or 5% dextrose in water were stored in glass intravenous bottles at temperatures between 6 and 38 degrees for 24 hr with a maximum loss of 18%. Stability was not affected by light. Solutions in contact with rubber stoppers, plastic intravenous bags, or plastic administration sets exhibited decreased nitroglycerin concentration characteristic of sorption. Nitroglycerin concentrations decreased to a greater extent when the administration sets were equipped with plastic burets. Brief contact of nitroglycerin solutions with a plastic syringe did not result in decreased concentration. The stability of intravenous nitroglycerin solutions packaged in glass was not dependent on light, the vehicle, or the source of nitroglycerin. Contact with rubber or plastic surfaces should be minimized.