Studies in rats with a clinically relevant form of peritonitis indicate that tissue adenine nucleotide levels do not decrease in the early stages of sepsis. In contrast, hepatocellular active transport appears to be depressed even in the very early stages of sepsis. In late sepsis, however, tissue adenine nucleotide levels decrease significantly because of inadequate perfusion associated with peritonitis. Reticuloendothelial function (RES) is also significantly depressed at the late stages of sepsis. Administration of saline, glucose, or ATP-MgCl2 alone following sepsis does not produce any beneficial effects on survival. However, administration of high concentrations of ATP-MgCl2 together with hypertonic glucose results in a significant improvement in the survival of animals. This treatment regimen restores cellular ATP levels and also restores the depressed RES function to normal within three hours. Thus, extirpation of the lesion producing the septic process, combined with metabolic support, proves helpful without antibiotic treatment. © 1984.