The Lythraceae contribute eight genera and 41 species to the flora of the Antilles. Two genera, Ginoria and Haitia, and twenty-two species are endemic to the region. A summary of the distribution of each genus among the islands of the Greater Antilles is presented, together with an estimate of center of origin and mode and direction of introduction. Cuphea (15 species) and Ginoria (13 species) are best represented. Results of phylogenetic analyses for Rotala, Cuphea, and Ginoria aid in understanding the nearest relationships and geographic sources of the Antillean members of these genera. They suggest that Rotala was introduced twice from different directions and Cuphea was introduced from eastern South America a minimum of five to eight times into the Greater Antilles and at least three times into the Lesser Antilles. A paraphyletic Ginoria and Haitia, which is nested within the most derived species of Ginoria, are the result of adaptive radiation in situ in Cuba and Hispaniola from an undetermined ancestor. The biogeographic patterns of the Lythraceae in the Caribbean primarily have been established following chance, multiple, long-distance dispersal events from multiple directions. Highly vagile seeds and self-compatibility most likely enhanced their successful dispersion and establishment. Vicariance is not required to explain the distribution of Lythraceae in the Antilles.