The cardiorespiratory response to prolonged work was investigated in 15 patients (age 51 ± 5.6) after transmural myocardial infarction; the patients had angina pectoris. Based on an individually determined pain threshold heart rate the following two relative work loads were obtained; 55 per cent and 90 per cent of threshold heart rate. Training was monitored using the 10-channel Siemens radio-telemetry system, and consisted of 30 minutes continuous pedalling, twice per week. Pretraining results showed a substantial increase in heart rate (HR 12± 8.2) and systolic blood pressure (SBP 15 mmHg) between the 5th and the 10th minute of work and decrease in O2 consumption (Vo2 1/min) and 02 pulse between the 15th and 30th minute of exercise. Training resulted in the following changes: Decreased heart rate at rest and during work (P<0.01). Systolic blood pressure did not rise up to the 15th minute of work. Oxygen consumption increased gradually, reaching a steady state after 15 minutes of work. O2 pulse increased gradually and remained constant during the last 15 minutes of work. SBP× HR product decreased significantly (P <0-05-0-01) at rest and during work. Favourable changes in minute ventilation and ventilation equivalent indicate improved respiratory adjustment. Clinically there was a pronounced decrease in severity and frequency of angina pectoris along with increased work time before onset of pain. The data show that intensive prolonged training may result in improvement of the physiological adaptive mechanism of patients with angina pectoris to continuous physical stress.