Twelve patients with stable angina and reproducible depression of the ST-segment during bicycle exercise of at least 0.15 mV were assessed in a double-blind randomized cross-over study. Patients were treated either with 50 mg isosorbide-5-mononitrate (IS-5-MN) daily or 2 X 20 mg nifedipine retard daily or the combination of both drugs for 2 weeks. The sum of ST-segment depression at maximal exercise was reduced by nifedipine and IS-5-MN to the same amount, while ST-segment reduction was highest during treatment with the combination of both drugs. The best exercise duration and maximal working capacity were also recorded during combination treatment. However, patient appreciation concerning efficacy and side-effects was best with nifedipine, slightly worse with IS-5-MN, and only one patient judged the combination of both drugs as good.