Guava is a genus of about 100 species of tropical shrubs and small trees in the myrtle family Myrtaceae. Native to Mexico and Central America, northern South America and parts of the Caribbean, it is now cultivated throughout the tropics. Numerous references in medical research identify guava as Psidium guajava.

They are typical Myrtoideae, with tough dark leaves that are opposite, simple, elliptic to ovate and 5-15 cm long. The flowers are white, with five petals and numerous stamens.

In several tropical regions, including Hawaii, some species (namely Cattley guava a.k.a. strawberry guava, P. littorale) have become invasive weed shrubs. On the other hand, several species have become very rare and at least one (Jamaican guava, P. dumetorum), is already extinct.

The genera Accara and Feijoa (= Acca, pineapple guava) were formerly included.