One probable extinction and one range reduction of eastern Pacific reef-building hydrocoral (Millepora) species mark the first documented cases of species eliminations resulting from the worldwide 1980s coral reef bleaching events. Two of 12 Panamanian coral species were eliminated suddenly from their former ranges by prolonged high sea temperatures during the 1982-83 El Niño-Southern Oscillation event. Three conditions contributed to their demise: high sensitivity to sea warming, populations confined to a small geographic area, and bathymetric restriction to the euphotic zone (</=20 meters depth) where El Niño sea warming had its greatest effect.