The heat shock or stress response is a highly conserved primary cellular response to injury. Synthesis of stress proteins (also called "heat shock proteins") is an integral component of this response. Protection from various forms of sublethal stress following increased production of stress proteins has been demonstrated in a number of systems, including the retina. This immunocytochemical study demonstrates the synthesis, accumulation, and redistribution of the 70-kD stress protein following spinal cord injury in rats. The observations confirm that stress protein production is a fundamental feature of the molecular response of the spinal cord to injury, and raise the possibility that augmentation of this response could enhance posttraumatic neuronal survival.