Varicella is an infrequent but potentially severe infection in adult HIV-infected patients. We reviewed five cases of varicella in HIV-seropositive men; two were complicated by severe headache and meningismus, and one of these patients also had hepatitis and thrombocytopenia. All five patients responded well to acyclovir therapy, but one patient had dermatomal zoster 2 years later, and another failed to have detectable antibody after infection. We also performed a serosurvey on 181 consecutive HIV-infected patients presenting themselves for evaluation. A total of 95% of these patients had demonstrable antibody to varicella-zoster virus. Immune status to varicella did not correlate with the declining CD4 count, which was well preserved even in patients with fewer than 200 CD4 cells/mm3.