The Yage Letters, first published in 1963, is a collection of correspondence and other writings by Beat Generation authors William S. Burroughs and Allen Ginsberg.

[1] Most of the letters date back to 1953[1] and chronicle Burroughs' visit to the Amazon rainforest in search of yagé (ayahuasca), a plant with near-mythical hallucinogenic and some say telepathic qualities.

The anarchic "Roosevelt After Inauguration", a savage parody of American politics in which "a purple-assed baboon" is appointed to the United States Supreme Court, was omitted from the original edition of the book on the grounds it might be considered obscene; it was subsequently issued as a chapbook later in the 1960s and was later published in the small volume Roosevelt After Inauguration and Other Atrocities with two political essays.

is considered a poem by some and is an early demonstration of the "cut-up technique" espoused by Burroughs in the 1960s, shuffling together fragments of sentences and thoughts from other texts to create a surreal new narrative.

According to the back cover of a 1990s edition of the book, Burroughs and Ginsberg began compiling the work in late 1953, not long after the original set of letters was written, but it was not published for nearly a decade.