Background：Pain in the form of acute neuritis and postherpetic neuralgia is by far the most frequent and most debilitating complication of herpes zoster. The pain of acute herpes zoster may be severe, but it is usually transitory. Some patients, with the elderly at particular risk, go on to develop postherpetic neuralgia. Postherpetic neuralgia is often severe and, unfortunately, refractory to most forms of treatment. Objective：The purpose of this study was to compare the severity of acute pain and incidence of postherpetic neuralgia by age group, dermatomal distribution and the presence and absence of associated diseases. Methods：We observed the severity of initial pain, changes in severity of pain during treatment, and the incidence of postherpetic neuralgia in 105 patients with herpes zoster with the same therapeutic measures (systemic steroid, acyclovir, analgesics, and tricyclic antidepressant). And we compared them by age group (the young & middle age vs the old age group), dermatomal distribution(trigeminal, cervical, thoracic, and lumbosacral), and the the presence and absence of associated diseases respectively. And we also analyzed the relationship between the incidence of postherpetic neuralgia and the severity of initial pain. Results：1. Sixty-six patients (63%) of the total number of subjects complained of initial `severe pain', and the incidence of initial `severe pain' was significantly higher in the old age group (78%) compared with the young & middle age group (48%). But, there was no significant difference by dermatomal distribution and the presence and absence of associated diseases. 2. The duration of pain was 2-4 weeks in 27 patients (26%), 1-2weeks in 26 (25%), more than 8 weeks(postherpetic neuralgia) in 24 (23%). 3. The mean comparative value of the severity of pain was 38% of initial pain after 3 days of treatment, 22% 1 week, 15% 2 weeks, 8% 4 weeks, and 5% 8 weeks, respectively. But, there was no significant difference in changes of severity of pain by age group, dermatomal distribution, and the presence and absence of associated diseases. 4. The incidence of postherpetic neuralgia was significantly higher in the old age group (35%) compared with the young & middle age group (11%). But there was no significant difference by dermatomal distribution and presence and absence of associated disease. And the incidence of postherpetic neuralgia was also significantly higher in the initial 'severe' pain group (33.3%) than in the initial 'mild' pain group (14.3%) and the `moderate' pain group (3.1%). Conclusions：Older patients with herpes zoster showed severer initial pain and a higher incidence of postherpetic neuralgia. But there was no significant difference in the severity of initial pain and incidence of postherpetic neuralgia by dermatomal distribution and the presence and absence of associated diseases. And patients with initial severe pain showed a higher incidence of postherpetic neuralgia than those with mild and moderate pain, respectively. (Korean J Dermatol 2000;38(3)：314~321)