Varicella-zoster virus (VZV) infections are among the most common viral diseases characterized by recurrent episodes alternating with asymptomatic periods. VZV reactivation is believed to be induced by the impairment of the host's cell-mediated immune system; however, the precise mechanisms involved in the latency period and reactivation of herpes viruses in the infected host are not yet fully elucidated. We assessed the immune functions in noncompromised patients with typical herpes zoster to investigate the immunological status during the process of reactivation of VZV. The results indicated depressed immune functions in the early stage of VZV reactivation with gradual improvement during the recovery phase. These findings are in accord with the clinical course of herpes zoster and suggest a possible therapeutic trial.