Three Japanese patients with trigeminal trophic syndrome, a rare dermatosis in Japan, were reported. Cutaneous lesions were a long-standing ulcer and destruction of the right ala nasi in case 1, a persistent deep ulceration on the forehead after a small trauma in case 2, and development of small, discrete ulcers on the right forehead during the treatment of a postherpetic neuralgia in case 3. A protective device was very effective in one patient.