This report describes Gumbo Limbo virus, a new Group C arbovirus from the south Florida everglades and the first UnitedStates representative of this group. Serological crossing was demonstrated between Gumbo limbo and 10 of the 12 previously known Group C viruses, with indications of an especially dose relationship to Nepuyo. It is dearly distinguishable from Nepuyo, however, by hemagglutination and neutralization tests.