Four accessions of Stylosanthes hamata (L.) Taub. collected from the southeast coast of Florida and one from Australia were inoculated with a specific Rhizobium strain and grown in virgin Oldsmar fine sand soil with and without added nitrogen. Added N (equivalent to about 180 kg N/ha) significantly reduced the total yields in some cases. The best growth without added nitrogen was shown by plants collected from near Riviera Beach. The differential response of S. hamata to added nitrogen suggests the need for care in the use of nitrogen in grassland when S. hamata is present.