Sixteen endemic Hawaiian species of Lysimachia, formerly referred to as subgenus Lysimachiopsis, form a morphologically distinct and monophyletic group within the genus. This group has radiated in various habitats, and most species are endemic to a single island. To reconstruct phylogenetic interrelationships between the recognized taxa, we conducted phylogenetic analyses of 12 species of Lysimachia subgenus Lysimachiopsis using nuclear ribosomal DNA from two (ETS, ITS) and plastid DNA from five markers (rpl16, rpl20-rps12, rps16, trnH-psbA, trnS-G). A Bayesian analysis using all molecular data indicated that there are two major evolutionary lineages of Hawaiian endemic Lysimachia. The results also provide new insights into the evolutionary history of the problematic L. hillebrandii/L. remyi complex, showing that L. hillebrandii and L. waianaeensis are closely related but that L. ovoidea is more distantly related and belongs to the other major lineage. Furthermore, L. remyi subsp. remyi and subsp. subherbacea are both closely related to L. maxima, but L. remyi subsp. caliginis and subsp. kipahuluensis belong to the second major lineage. Our results also indicated that earlier taxonomic treatments of the group need to be partially revised to reflect evolutionary relationships. A brief discussion on biogeography of the group is presented. The new combinations Lysimachia kipahuluensis subsp. caliginis and Lysimachia remyi subsp. maxima are made.