Gymnocalycium, normally known as chin catcus, occurs as genus of astir Seventy South American species of cacti. A genus title Gymnocalycium (from either Greek, "naked calyx") refers to the flower buds bearing no hair or even spines.

Their independent locality of distribution is Argentina, part of Uruguay, Paraguay, southern Bolivia and part of Brazil. Virtually all mintage come like microscopic varying from either Four to 15 centimetres inside size. It is popular for their easily flowering habits, although a flowers are generally brilliantly coloured.

A genus Brachycalycium Backeb. has been brought into synonymy with this genus.