TIHKAL: The Continuation is a 1997 book written by Alexander Shulgin and Ann Shulgin about a family of psychoactive drugs known as tryptamines. A sequel to PIHKAL: A Chemical Love Story, TIHKAL is an acronym that stands for "Tryptamines I Have Known and Loved".

Alexander Theodore "Sasha" Shulgin was an American medicinal chemist, biochemist, organic chemist, pharmacologist, psychopharmacologist, and author. He is credited with introducing MDMA, commonly known as "ecstasy", via academic journals and papers to psychologists in the late 1970s for psychopharmaceutical use and for the discovery, synthesis and personal bioassay of over 230 psychoactive compounds for their psychedelic and entactogenic potential.