This paper is a compilation of information on the taxonomy and evolution of the genus Macaca. The various classifications of the macaques since 1916 are provided. Descriptions of all known extant species and general characteristics of each species group are reviewed, and hybridization between the different species discussed. Details are given of the geographic distribution of all species, including the habitats utilized. The available information on the fossil record is collated and this is followed by a discussion of the current interpretations of distributions, in relation to evolution and dispersal of the genus. The paper ends with a synopsis and conclusions which point out areas where further research is needed.