Varicella-zoster virus (VZV) causes both chickenpox and zoster. Fundamental to their prevention is an understanding of the natural history of VZV infection. This is a compilation of papers presented in March 1999 in Osaka, Japan, by internationally renowned researchers studying varicella-zoster virus and a vaccine used to prevent disease caused by this virus. The aim of the meeting was to explore progress made in basic and molecular biology of VZV and current understanding of latent infection and reactivation. Data concerning immune responses to VZV, mechanisms by which virus latency are controlled, and the latest information on vaccination to prevent varicella and zoster are presented and discussed.