The effectiveness of epidural spinal electrical stimulation has been studied in 14 patients with severe intractable angina unresponsive to standard therapies including bypass grafting. After implantation of the neurostimulator units the patients were assessed by a symptom questionnaire, treadmill exercise testing and right atrial pacing. There was a significant improvement of symptoms and GTN consumption fell markedly. With the neurostimulator on, exercise duration increased from a mean (CI) of 414 (153) to 478 (149) s, and total ST segment depression was less both at maximum exercise (7.1 (4.5) vs 5.6 (4.2) mm) and at 90% of the maximum control heart rate (3.5 (3.7) vs 2.6 (4.3) mm), with similar rate-pressure product at maximum exercise. With right atrial pacing the maximum heart rate reached before onset of angina was increased (143 (14) to 150 (7) b.min-1) and total ST segment depression was less at all heart rates. Benefit has persisted in some patients for over 2 years without any apparent adverse sequelae. Epidural spinal electrical stimulation is, therefore, an alternative therapy for some patients with intractable angina which has not responded to standard therapies.