The present work confirms previous observations made by others that heat shock is followed by a period of protection against tissue injury. Furthermore, this protection against associated with HSP 72 production. We have identified some detrimental effects of heat shock as a technique for induction of the HSR. Clearly there exists in living tissues a highly conserved, latent cellular mechanism that can be rapidly activated by stress, which can provide useful protection against additional stressful conditions. The ability to control the expression of this response should enable one to protect cells, tissues, and organisms against situations in which tissue injury is anticipated.