Psychophysiological reactivity and cardiovascular functioning were assessed in 40 patients with coronary heart disease before and after taking part in either a Type A modification training program or a control condition. Treated patients showed an overall attenuated heart rate (HR) response and prolonged diastolic time to mental stress performance, during recovery and rest periods, as compared lo control patients. No other measure, including impedance-cardiography-derived measures, differentiated the two groups. The treatment group showed reduction from before lo after treatment in 24-hr minimum IIR level and decreased frequencies of premature ventricular contractions, whereas the control group showed an opposite trend. Results from an exercise test suggested the same direction for resting IIR and double-product levels. The two groups did not differ in maximal systolic and diastolic blood pressure or in maximal double-product levels, despite a differential development, in favor of the treatment group, in maximal work capacity.