Frequent widespread episodes of coral bleaching have made researchers aware of the sensitivity of reef corals to moderately elevated temperatures and led us to investigate mechanisms of temperature stress tolerance in this group. One such mechanism may be the induced synthesis of heat shock proteins (hsps), which have been shown to play a role in thermotolerance in other organisms. However, induced synthesis of hsps in scleractinian corals was not reported until recently. Experiments were conducted in which Montastraea faveolata was exposed to high temperatures (up to 35{deg}C) for short periods (2 h). Under the conditions tested, the corals produced seven different hsps with approximate molecular weights of 95, 90, 78, 74, 33, 28, and 27 kDa. Another zooxanthellate species, the sea anemone Aiptasia pallida, also synthesized hsps during temperature stress, but fewer and with different molecular weights (82, 72, 68, and 48 kDa) than those produced by Montastraea. It now remains to be determined whether hsps are involved in differences in thermotolerance and susceptibility to bleaching within and between the various species of Montastraea, and between species of reef cnidarians.