The plasma levels of homocysteine (Hcy),vitamin B12 and folic acid were measured in a total of 101 patients with herpes zoster (observation group) before treatment and 100 healthy controls (control group).And the plasma level of Hcy was also measured in observation group after treatment.There was a significant increase of Hcy level in observation group versus control group (P ＜0.01).And the levels of VitB12 and folic acid did not fluctuate (P ＞ 0.05).The occurrence rate of hyperhomocysteinemia and the level of Hcy differed in age group,onset site and pain severity (P ＜ 0.05).No significant differences existed between gender or onset site (P ＞ 0.05).The level of Hcy significantly decreased after treatment versus before treatment (P ＜0.01).Plasma Hcy significantly increased in patients with herpes zoster.And it was correlated with age,lesion extent and pain severity.However,there was no correlation with gender,onset site or levels of vitamin B12 and folic acid.