The present report is limited solely to a study of the frequency of "functional disturbances" of the heart and to a consideration of their clinical importance. Their mechanism and treatment are not discussed, though the early recognition and proper treatment of these disturbances are very important. Neither is consideration given to the common superimposition of functional disturbances on organic heart disease, which may be aggravated thereby and often cannot be effectively treated until the functional element is overcome. One should not consider functional disturbances unimportant merely because they are not organic in origin. Too often the mental and physical distress caused by functional heart disease results in either partial or total disability, and too often it causes a disruption of the family and social life of the patient. The term disturbance is purposely used in preference to the word disease. "Disease" has a serious connotation to many people, and its