Oreocereus hempelianus is a species of cactus native to Peru and Chile.

Oreocereus hempelianus grows with spherical to elongated gray-green shoots that branch from the base and reaches heights of 30 to 40 cm (12 to 16 in).

[2] Oreocereus hempelianus is common in the Arequipa region of Peru and Tarapacá, Chile, at altitudes of 2,500 to 3,500 meters.

[3] The specific epithet hempelianus honors the German cactus lover and businessman Georg Hempel.

[1] Foreign language common names are "Achacaño" and "Arequipa".