French Frigate Shoals represents a relatively unpolluted tropical Pacific atoll system with algal assemblages minimally impacted by anthropogenic activities. This study qualitatively assessed algal assemblages at 57 sites, thereby increasing the number of algal species known from French Frigate Shoals by over 380% with 132 new records reported, four being species new to the Hawaiian Archipelago, Bryopsis indica, Gracilaria millardetii, Halimeda distorta, and an unidentified species of Laurencia. Cheney ratios reveal a truly tropical flora, despite the subtropical latitudes spanned by the atoll system. Multidimensional scaling showed that the flora of French Frigate Shoals exhibits strong similarities to that of the main Hawaiian Islands and has less commonality with that of most other Pacific island groups.