We performed the in situ hybridization (ISH) study of the smear cells taken from the patients of herpes zoster. We used the biotinylated EcoRI-B, H fragment of varicella-zoster-virus (VZV) DNA as the probe. In the control study of ISH VZV-infected cells showed strong staining, but no staining was observed in the infected cells by other herpes virus. We examined the smear cells of 19 patients of herpes zoster and 2 patients of herpes simplex by ISH. 30 of the 35 specimens of herpes zoster was positive by ISH. We detected VZV DNA in the smear cells of all cases of the bullous stage, but the sensitivity was about 75% in the later stage. Smear cells of herpes simplex was not stained by ISH. We also performed virus isolation of 13 cases of herpes zoster. But the sensitivity of ISH was higher than that of virus isolation in the other stages of herpes zoster. This method is very simple and can be completed in about 1 hour. It also has high specificity and sensitivity. So this method is very useful for the rapid diagnosis of VZV infection.