Antibody responses to varicella-zoster virus (VZV) were serially investigated by the complement-fixation test in 72 Japanese of both sexes, suffering from herpes zoster (HZ), but otherwise healthy. Our objective was to elucidate whether there were mutual relationships among severities of skin lesion, maximum antibody titers to VZV, and duration of treatment for acute herpetic pain (AHP). Patients were divided into 3 groups: mild group (n = 26), moderate group (n = 26) and severe group (n = 20), according to the severity of the skin lesions. The 3 groups did not differ significantly with respect to age (P greater than 0.6). All patients were treated with regional sympathetic nerve blocks (SNBs) until pain relief was achieved. The durations of treatment for AHP became significantly longer as HZ increased in severity; the mean log10 durations of treatment (+/- S.E.) for the mild, moderate, and severe groups were 1.383 +/- 0.037, 1.616 +/- 0.055, and 1.888 +/- 0.069 days, respectively (P less than 0.01 for the mild group vs. the moderate group, and P less than 0.001 for the moderate group vs. the severe group). Irrespective of age, the maximum antibody titers closely paralleled the severities of the skin lesion of HZ; the mean maximum log2 antibody titers (+/- S.E.) for the mild, moderate, and severe groups were 5.12 +/- 0.24, 6.73 +/- 0.20, and 8.00 +/- 0.18, respectively (P less than 0.001 for the mild group vs. the moderate group and for the moderate group vs. the severe group).(ABSTRACT TRUNCATED AT 250 WORDS)