Density of adult Diadema antillarum was assessed on live coral patch reefs and dead Acropora cervicornis rubble patches next to Loggerhead Key, Dry Tortugas National Park, Florida, USA in June 2009. Mean density on live coral patch reefs (0.49 individuals m^-2) was not statistically different from mean density on dead A. cervicornis rubble patches (0.30 individuals m^-2), while the highest density on live coral patch reefs (1.39 individuals m^-2) was twice that of dead A. cervicornis rubble patches (0.63 individuals m^-2). A significant negative correlation was found between two-dimensional area and density of adult D. antillarum on live coral patch reefs, while no significant correlation was found between two-dimensional area and density of D. antillarum on dead A. cervicornis rubble patches. No significant correlation was found between rugosity and density of D. antillarum on dead A. cervicornis rubble patches. While adult densities are higher than after the mass mortality event of the 1980s, they have not recovered to pre-mass mortality levels. The ability of D. antillarum to occupy completely dead rubble may help in the long-term reestablishment of the species on live reefs by allowing it to utilize additional areas for possible spawning and juvenile recruitment.