Soursop (also called graviola, guyabano, and in Hispanic America guanábana) is the fruit of Annona muricata, a broadleaf, flowering, evergreen tree. It is native to the tropical Americas and is widely propagated. It is in the same genus, Annona, as cherimoya and is in the Annonaceae family.

The soursop is adapted to areas of high humidity and relatively warm winters; temperatures below 5 °C (41 °F) will cause damage to leaves and small branches, and temperatures below 3 °C (37 °F) can be fatal. The fruit becomes dry and is no longer good for concentrate.

With an aroma similar to pineapple, the flavor of the fruit has been described as a combination of strawberries and apple with sour citrus flavor notes, contrasting with an underlying thick creamy texture reminiscent of banana.

Soursop is widely promoted (sometimes as graviola) as an alternative cancer treatment, but there is not enough reliable medical evidence that it is effective for treating cancer or any disease.

Soursop leaves, skin, flesh, and seeds contain annonacin, a compound under preliminary research for its potential neurotoxicity.

Annona muricata is a species of the genus Annona of the custard apple tree family, Annonaceae, which has edible fruit. The fruit is usually called soursop due to its slightly acidic taste when ripe. Annona muricata is native to Mexico and Central America but is now widely cultivated – and in some areas, becoming invasive – in tropical and subtropical climates throughout the world, such as India.

Annona muricata is a small, upright, evergreen tree that can grow to about 10 m (33 ft) tall.

Its young branches are hairy. The leaves are oblong to oval, 8 to 16 cm (3.1 to 6.3 in) long and 3 to 7 cm (1.2 to 2.8 in) wide. They are a glossy dark green with no hairs above, and paler and minutely hairy to no hairs below. The leaf stalks are 4 to 13 mm (0.16 to 0.51 in) long and without hairs.