In view of the growing interest in unusual forms of cardiac arrhythmia and their relation to focal infections on the one hand and to thyreopathic disturbances on the other, it has seemed to us worth while to record a case in which remarkable disturbances of cardiac rhythm were encountered in association with (1) peridental, maxillary and tonsillar infection, and (2) minute adenomata of the thyroid gland; and in which marked improvement followed treatment of the infected foci and partial thyroidectotmy. A. CLINICAL HISTORY Anamnesis. —The patient, K. I. N., a salesman, aged 51, married, applied for a general diagnostic study on Feb. 11, 1918. Family History. —Father died at 90, cause unknown; mother died at 47, at childbirth; one brother, older than the patient, has suffered from a nervous breakdown and has had some thyroid trouble; one sister died of thyroid disease; a second sister has never been robust. Married