To evaluate the possibility of improving clinical practice in the treatment of angina pectoris, the duration of relief of pain with isosorbide dinitrate (ISDN) oral spray and sublingual tablets were compared in elderly patients with chronic stable angina pectoris. Nine patients (mean age 67 years) were studied in a randomized crossover trial. The patients underwent bicycle ergometry, which resulted in typical chest pain associated with electrocardiographic ST-segment depression in all 9. The patients received ISDN oral spray or sublingual tablets immediately on termination of exercise. At least 6 hours later another ergometry test was performed and the patients were crossed over to the other drug. ISDN spray relieved pain in all patients at a mean duration of 61.6 +/- 24.4 seconds after administration, whereas the duration of relief of pain by ISDN sublingual tablets was 112.4 +/- 70 seconds. The difference was highly significant (p less than 0.0005). It is concluded that clinical practice of treatment of angina pectoris in the elderly can be improved by using ISDN oral spray rather than sublingual tablets. The spray is effective at twice the rapidity of the sublingual tablet.