This study is based on measuring the d.c. (direct current) skin conductance of the acupuncture points representing the heart on the external ear. The subjects were 30 healthy volunteers and 20 cardiac patients. The results obtained showed that the skin resistance of the heart acupuncture loci on the auricle of the cardiac patients were markedly reduced when compared with that of the healthy controls. The value of this method of auricular electroacupuncture diagnosis is discussed.