We present the first in a series of five papers from the Departments of Biochemistry and Surgery, State University of New York at Buffalo, in this issue, and plan to have the remaining papers in the series in the next four issues of the Journal. The first two papers are longitudinal studies of a single trauma patient from admission to death; the other three are collective studies on survival versus death from a septic trauma episode and the observations associated with amino infusion, albumin infusion, and the response of the plasma proteins. (Eds.) This is a longitudinal study of the basal cardiopulmonary function, plasma concentrations, and splanchnic extractions of a patient with severe trauma with associated oliguric renal failure, who was supported on 5% glucose and albumin from admission to death with a massive pelvic abscess. Twenty-nine blood cultures were negative. The measurements show, apart from the initial and terminal states, adequate cardiopulmonary function with vigorous support. They also show that the post-shock trauma adaptive phase (days 4 to 10) was one of high but reducing splanchnic extraction of a largely balanced mixture of amino acids in association with rapidly decreasing carbohydrate and increasing fat catabolism. Compared to overnight normal fasting subjects, the means of 13 basal arterial analyses on the patient were significantly lower for threonine, serine, glycine, alanine, isoleucine, ornithine, lysine, histidine, and arginine, and significantly higher for phenylalanine, tryptophan, lactate, free fatty acid, glucose, acetoacetate, and triglycerides. The tyrosine-phenylalanine ratio was much reduced and the tryptophan to LNAA ratio much increased. Some plasma substances showed a marked increase in concentrations starting at day 10 (proline, an unknown 'fast cystine,' glutamate, aspartate, α aminobutyrate). Clinically, days 10–11 were considered a transition period between the trauma adaptive phase and initial septic phase. The septic phase was one of rapidly reducing fat catabolism in association with increasing glucose catabolism and splanchnic extraction of a largely unbalanced mixture of amino acids which was rich in tryptophan and proline and deficient in isoleucine. Such a mixture would reduce protein synthesis while stimulating gluconeogenesis. The statistical significance of the preceding statements and associated changes is explored in detail on more than 6,000 plasma analyses. The observed changes are consistent in the septic phase with a muscle fuel deficit which enhances branched chain oxidation while relating muscle atrophy to liver failure to peripheral circulatory failure to the lethargic state. The fact that less splanchnic catabolism of amino acids accompanies increased splanchnic concentration of substances which are good muscle fuels implies that the energy needs of muscle have a primary role in substrate priorities in the trauma-septic state, whereas the splanchnic system has a secondary role. This latter interaction is defined as a muscle-liver-fuel cycle.