World 4 (Dr. Mario World)

World 4 is a haunted forest world in Dr. Mario World. It features a Ghost House on the world map. It is available since the initial version of this game.

When an area is cleared, Boos and Peepas appear. The viruses featured in the regular stages are red, green and light-blue.

Stage names in bold red text are labelled as hard stages in the game.