The effectiveness of Nitroderm TTS 5 and Nitroderm TTS 10 in stable effort-induced angina pectoris was assessed by measuring the tolerance of 20 selected in-patients to cycloergometric symptom-limited tests. During the week preceding the trial previous anti-anginal treatment was gradually withdrawn except for short-acting nitrates. Patients were also familiarized with ergometric laboratory environment. The trial started with a 24-h control period when placebo was given single-blind to each patient. A double-blind cross-over design was then followed, two groups of 10 patients each being subjected successively to two sequences of therapy. By means of the double-dummy technique, Nitroderm TTS 5 or Nitroderm TTS 10 and matching placebos were applied simultaneously once daily for 24 h on two different days. Resting heart rate and blood pressure were measured before starting each exercise test, which was performed 3 h after placebo as well as 3 and 24 h after Nitroderm TTS application. The results of the tests were evaluated in terms of maximum workload, duration of exercise and total work performed for each of the two doses administered and compared with the corresponding baseline values. When compared with placebo both Nitroderm TTS doses produced a significant change (P less than 0.01) in the assessment variables. After application of the active treatment, duration of exercise, total work performed and maximal workload were increased while lying and standing blood pressures were decreased. There was no significant difference between the two doses of Nitroderm TTS in the assessment variables, except for systolic blood pressure and lying heart rate 3 and 24 h, respectively, post-dosing.(ABSTRACT TRUNCATED AT 250 WORDS)