Although the importance of the exercise prescription for ischemic heart disease has been recognized for a long time, ischemic heart disease patients were often located in reduced physical activities due to the fear that physical training could result in further deterioration in cardiac function. Swimming in particular was rarely allowed for those patients, despite the valuable advantages as an overall physical conditioning and leisure time activity. In this study, the swimming program invo1ving water gymnastics was added as a complement to an already established active, supervised conditioning program, which consisted of a 90min. exercise period held 3 times per week including a variety of exercises: walking, jog-walk, calisthenics, gymnastics, modified volleyball, badminton, table tennis, mini-tennis, etc. Twenty male patients aged 44 to 70, recovering from myocardial infarction or suffering from angina, were engaged in the swimming program. All patients in the treadmill or bicycle-ergometer tests performed before participation in the swimming program showed over 100 watts in their exercise capacity. Although a medical examination was required for participation, our attention was also given to physiological and clinical profiles of individuals, and swimming was usually prescribed on a mass basis, because group programs provide excellent opportunities for motivation, Which has often been neglected in such therapy. Main1y, the breast and back strokes, which require no restrictions in respiration, were a part of the endurance oriented training; i.e., a low resistance and high repetition program. ECG-telemetory was performed during all water activities and the recovery phase. Swimming was to be stopped at the symptom-limited point, as defined by fatigue or clinical symptoms or electrocardiographic abnormalities, but no one was stopped by the examiner even in the 100m breast stroke. Thus, no adverse cardiovascular cases occurred during the swimming session as well as in the regular training program. Detailed evaluation of clinical data obtained during this program revealed that patients were able to perform water gymnastics and swimming safely, i.e., with a modest heart rate in the range of 90-120 beats per min, and modest blood pressure of l00-160mmHg. All of the patients claimed that they felt better refreshed after the swimming. Although the study is considered to be still in the experimental stage, this study would provide a support for the proposal that swimming can be used safely in the treatment of selected patients with coronary heart disease, and is especially valuable for well-motivated cardiac rehabilitation patients in a program which needs months to years to maintain at a required level of exercise.