Natural hybridization has been frequently reported in Cactaceae, but there are few studies on the impact of hybridization in the evolution and diversification of this family. The majority of the studies that have addressed this subject have been restricted to the subfamily Opuntioideae. Little is known about the role of hybridization on the more diverse subfamily Cactoideae. This paper discusses putative examples of hybrid lineages in subfamily Cactoideae, focussing on examples of lineages for which hybrid or introgressive origin have been confirmed or deduced from morphological and molecular studies. These examples suggest that natural hybridization may have played an important role in the evolution and diversification of taxa in Cactaceae, and further studies of hybrid lineages may provide us with important insights on the evolution of this family.