Psidium is a genus of trees and shrubs in the family Myrtaceae. It is native to warmer parts of the Western Hemisphere (Mexico, Central and South America, the West Indies, and the Galápagos islands). Many of the species bear edible fruits, and for this reason several are cultivated commercially. The most popularly cultivated species is the common guava, Psidium guajava.

This genus was described first by Linnaeus in 1753.

Fossils are known from the Paleogene of Patagonia.

78 species are accepted.