World D is the fifth and final secret world that was featured in the game Super Mario Bros.: The Lost Levels. Like the other secret worlds, it was left unused in Super Mario Bros. Deluxe. When Bowser is defeated at the end of World D-4, Princess Toadstool is saved, and, as such, Mario and Luigi beat the game.
 Level Information
||A level similar to World 8-1. In the original FDS version, it is a snowy level, but in the SNES remake, its a grassy level.
||This level includes several upside down Piranha Plants.
||A level which has a brick wall in the background similar to World 8-3's. In All-Stars the wall is gone so the brick blocks are replaced with hidden blocks.
||A castle which starts out like World 8-4.
 Level maps
 The Lost Levels