Background: Body mass index (BMI) is associated with inflammation, immune response, and chronic pain. However, the impact of BMI on pain in patients with herpes zoster remains unclear. Objective: This study aimed to investigate whether BMI was associated with acute pain and postherpetic neuralgia in patients with herpes zoster. Methods: We analyzed medical records of 620 patients with herpes zoster, aged ≥50 years, from 2017 to 2021. BMI was classified into three categories: underweight, BMI＜18.5 kg/m²; normal, 18.5 kg/m²≤BMI＜25.0 kg/m²; and obesity, BMI≥25.0 kg/m². Acute pain in patients with herpes zoster was assessed using a numeric rating scale (NRS) with scores ranging from 0∼10. To evaluate acute and chronic pain in patients with herpes zoster, we used a multiple linear regression model for the acute pain score and a multivariate logistic regression model for the incidence of postherpetic neuralgia. Results: The acute pain NRS score was higher in the underweight group than in the normal group (3.9 vs. 3.0, p=0.01). No significant differences were observed between the obese and normal-weight groups. In multivariate analysis, odds ratio for postherpetic neuralgia in the obesity group was 1.80 (95% confidence interval, 1.22∼2.66; p＜0.01) compared to the normal weight group. However, the odds ratio for postherpetic neuralgia in the underweight group was not significantly different from that in the normal-weight group. Conclusion: In patients with herpes zoster, being underweight was associated with a higher NRS score of acute pain than normal weight, and obesity was associated with a higher incidence of postherpetic neuralgia than normal weight. (Korean J Dermatol 2024;62(6):319∼326)