We have developed a Virtual Playground," which allows various activities such as virtual playground and virtual visiting areas for hospitalized children who can not usually go outside. A Virtual Playground system is composed of TV monitors, joysticks, cameras, video transmission devices, and a graphics workstation. In a Virtual Playground environment, children can experience what is impossible or difficult during their stay in a hospital. We have completed a couple of experiments already and discussed its effects.* In our recent work, we also introduced a simple version of the Cave display to the Virtual Playground system.