The transient addition of the cytosolic energy depletor 2-deoxy-glucose to cultures of rat prostate carcinoma cells blunted the induction of Hsp70 protein following exposure to elevated temperatures in a manner that appeared to parallel its effects on energy metabolism. While the reduction in stress-induced heat-shock protein expression by treatment with 2-deoxy-glucose had no effects on the acute loss of cellular viability after exposure to heat, the acquisition of thermotolerance in response to a conditioning stimulus was specifically repressed. Therefore, 2-deoxy-glucose will be a useful tool in the investigation of mechanisms that mediate immediate versus chronic responses to cellular stress, including the specific roles played by members of the heat-shock protein family of proteins. These results might have important implications in the design of protocols for the hyperthermic treatment of tumours.