The acute effects of coffee on exercise-induced angina were studied in 17 men with coronary artery disease using a double-blind treadmill protocol. Ingestion of either 1 or 2 cups of caffeinated coffee increased the exercise duration until onset of angina (8 and 12%, respectively, p less than 0.05), whereas decaffeinated coffee had no effect. The extent of ST-segment depression and the heart rate-blood pressure product at angina were similar after drinking caffeinated and decaffeinated coffee. Exercise duration until 0.1 mV of ST-segment depression, as well as the heart rate, blood pressure and double product at angina and at 0.1 mV of ST-segment depression were similar after drinking caffeinated or decaffeinated coffee. The mean serum caffeine levels (+/- standard deviation) after ingestion of 1 and 2 cups of caffeinated coffee were 1.97 +/- 1.0 and 3.89 +/- 1.6 micrograms/ml, respectively. The acute ingestion of 1 to 2 cups of caffeinated coffee had no deleterious effect on exercise-induced angina pectoris in patients with coronary artery disease.