THERE is no more controversial tumor occurring in the neck than that arising from the carotid body. The surgeon faced with the treatment of this entity faces conflicting opinions and whether such lesions are benign or malignant and whether or not any attempt should be made at removal. The crux of the matter lies in the close relationship of the tumor to the carotid artery. The serious sequelae that ensue from ligation of this structure, such as death and crippling permanent neurologic disturbances, have distressed all serious-minded surgeons. The thesis of our paper is, first, that carotid body tumors are not totally benign, as has been claimed, but if followed long enough are found to cause serious trouble either by local invasion of surrounding structures or by distant dissemination of disease; second, that with a better understanding of the precise relationship of the tumor to arterial wall components, it is