Abstract 1. 1. Pathologic causes of major trigeminal neuralgia frequently cannot be demonstrated in both the typical and the less clearly defined (atypical) cases. 2. 2. In the classic type of the disorder (Fothergill's disease), relief is most satisfactorily obtained by surgery. In the atypical syndromes surgery has generally been considered to be contraindicated; however, there are notable exceptions. 3. 3. From the literature it appears that trigeminal neuralgia may have a variety of causes: (1) infections, (2) ill-defined sclerotic changes, (3) neoplasms, (4) vascular anamolies, etc. 4. 4. Any attempt to classify the disease, aside from the classic and atypical forms, is almost impossible. However, two general groups can be recognized: (i) those which can be expected to respond to surgery; (2) those which cannot be expected to respond. 5. 5. In those atypical cases in which relief by surgery may be anticipated, the pain generally follows the distribution of one or more branches of the trigeminal nerve, and neurologic findings may or may not be present. 6. 6. In the cases reported a gross cause for the neuralgia was found which was consistent with the subjective complaints and the objective neurologic findings; relief was obtained by surgery, i.e., either by section of the posterior root of the trigeminal nerve or by removal of the cause.