Ololiuhqui (also spelled ololiuqui) is a hallucinogen, little known outside of Mexico, but perhaps the most common psychotropic drug used by the natives of that country.

In 1941, Richard Evans Schultes identified ololiuhqui as the seed of a species of morning glory, Rivea corymbosa. Its chemistry was first described on August 18, 1960, in a paper by Dr. Albert Hofmann.

The Nahuatl word ololiuhqui means "round thing," and refers to the small, brown, oval seeds of the morning glory, not the plant itself, which is called coaxihuitl, "snake-plant," in Nahuatl, and hiedra or bejicco in the Spanish language. The seeds, in Spanish, are sometimes called semilla de la Virgen.