On islands in the lower Florida Keys, endangered Key deer (Odocoileus virginianus clavium) aggregate in urban areas where deer densities are high, potentially increasing browsing impacts in these areas. To quantify impacts, we compared plant densities and diversity in hardwood hammocks located adjacent to (urban) and distant from (exurban) developed areas on islands with high (>17 deer/km²) and low (<1 deer/km²) Key deer densities. Although we detected no differences in total plant densities or diversity on islands with high densities of deer, we observed lower mean (±SE) densities of deer-preferred plant species within reach of deer in hammock stands in urban areas (84.9 ± 35.9/ha) than exurban areas (694.5 ± 428.4/ha). No such patterns were evident on islands with low deer densities. We also experimentally tested deer browsing intensity on islands of high deer density using potted plants. We found that mean (±SE) browsing pressures (measured as proportion of leaves remaining on potted plants) were higher on preferred plant species in hammocks near urban areas (0.451 ± 0.226) than exurban areas (0.591 ± 0.230). Stimuli (e.g., human handouts) that attract deer to urban locales should be controlled and further development restricted to deter heavy browsing pressures by Key deer near urban areas and to prevent degradation of state-imperiled hardwood hammock plant communities.