Maihuenia is a genus of cactus (family Cactaceae) and the sole genus of the subfamily Maihuenioideae, which is the smallest subfamily of the Cactaceae.

The genus comprises two cushion-forming, mucilaginous species.

They are found at high elevation habitats of Andean Argentina and Chile.

Its name is the Latinized version of maihuén, a local Chilean name for these cacti.

This Cactaceae article is a stub.