A substantial fraction of cells present within hard tumors experience extremely hypoxic and hypoglycemic conditions that can lead to phenotypic alterations such as increased metastatic potential and chemotherapeutic drug resistance. Little is known regarding the influence of anoxic aglycemia on tumor cell energy metabolism and viability, and no direct comparisons have been made between the effects of this form of metabolic stress on tumor cells and their tissue of origin. In this study, the effects of in vitro aglycemic incubation under N2 (with or without iodoacetate) on trypan blue exclusion, lactate dehydrogenase release, cell surface blebbing, ATP levels, and mitochondrial respiratory capacity of rat AS-30D ascites hepatoma cells and normal hepatocytes were measured. Under anoxic-aglycemic conditions, the period of incubation during which 50% viability was lost was 2 h for hepatocytes and 6-8 h for AS-30D cells. In contrast, the rate of anoxia-induced loss of ATP was comparable for the two cell types, and mitochondrial damage was actually accelerated in the tumor cells. These findings suggest that tumor cells are more resistant to anoxic cell death because of their greater ability to withstand deenergization and subcellular injury.