Effective stress conditioning can extend the safe cold storage time of rat kidneys to 48 hours. We demonstrated that planned induction of the stress response, by heat shock, can be used to stress condition the transplant organ and protect it against the damages of cold storage. A powerful and useful protective mechanism exists in a latent form in all cells. This mechanism can be rapidly activated in a controlled and planned way to allow tissues temporarily to resist injury. Through stress conditioning it is possible to provide a high level of protection in situations in which stress can be anticipated and planned for.