Trigeminal neuralgia is generally considered a unilateral disease, but a certain number of cases of bilateral pain having been recorded, and its occurrence being sufficiently frequent, the possibility of the development of this form should be thought of in each case of trigeminal neuralgia. The bilateral type most often begins on one side of the face, and after an intervening period of several months or years—more often the latter—the opposite side becomes affected. Accordingly, it is impossible to foretell definitely when symptoms develop on one side only whether or not the patient will suffer involvement on the other side. Hence it is important to attempt first to use trichloro-ethylene in the therapy of this disease; if surgical procedures are to be carried out later, it is imperative to be absolutely certain to conserve the motor root. To date there have been mentioned in the literature fifty-three cases of bilateral trigeminal