Chromosome counts for eight native species in six genera from Juan Fernández Islands, five native species in three genera from Tristan da Cunha, and three species in two genera from mainland Chile are presented and discussed. They include the only chromosome number reports for angiosperms from Tristan da Cunha and first counts for the endemics Robinsonia thurifera and Wahlenbergia larrainii (Juan Fernández), Agrostis carmichaelii, Acaena sarmentosa, A. stangii, and Nertera holmboei (Tristan da Cunha), and for Galium araucanum and Ourisia coccinea from Chile. Counts for Eryngium bupleuroides and Galium hypocarpium differ from earlier published reports.