The Lost Caverns of Tsojcanth is an adventure module for the Dungeons & Dragons fantasy role-playing game. It was written by Gary Gygax and published by TSR in 1982 for the first edition Advanced Dungeons & Dragons (AD&D) rules. The 64-page adventure bears the code “S4” (“S” for “special”) and is set in the World of Greyhawk campaign setting. It is divided into two parts, a 32 page adventure, and a 32 page booklet of monsters and magic items.