The genus Boa is represented in the Lesser Antilles by a range of fossil, recently extinct, and extant formsoccupying adjacent island banks in the center of the archipelago. Our multigene molecular phylogeny indicates reciprocal monophyly for these extant forms, and colonization from South America rather than Central America. The timing of the colonization of the Lesser Antilles by this genus indicates a late Miocene or Pliocene event, which is earlier than the Pleistocene event suggested for the Corallus treeboas, which are also represented by two extant nominal species. The compact distribution of Boa on adjacent island banks suggests a single colonization and radiation, but this cannot be tested due to widespread extinction of boas across the island banks.