Results are presented of a cytological survey of the Pteridophyte flora of Jamaica. Approximately 270 species or cytotypes were investigated, only a few of which have previously been investigated from other parts of the world. Several genera have been cytologically examined for the first time and their phylogeny has been discussed in the light of these findings. A number of species complexes and interspecific hybrids have been revealed. The overall statistics of the survey are compared with those compiled from an investigation of the Pteridophyte flora of Ceylon, by Manton and Sledge (1954). Finally, endemic species are discussed in the light of the cytological results and the time known to have been available for their establishment in Jamaica.