We sought evidence of oxidant-induced biological membrane damage in 43 resuscitated blunt trauma patients (average ISS, 36.9) within 2–6 hours of injury and before anaesthesia and surgery. The plasma levels of the lipid peroxidation products (conjugated dienes, CDs A 233nm) and malondialdehyde (MDA, nMol/ml) and the oxidant-inducing effect of the trauma plasma on normal FMLP-stimulated neutrophils were compared to those of control subjects. No differences were observed in the plasma levels of MDA (1.73 ± 2.15 vs. 1.45 ± 0.70 nMol/ml) and CDs (2.07 ± 2.16 vs. 1.28 ± 0.60 A 233nm). or on stimulated neutrophil superoxide production (26.4 ± 6.9 vs. 29.0 ± 6.2 nMol O2∼/2 x 106PMNs). These observations persisted when the patients were analyzed based on injury severity, the presence of long bone fractures, and the class of shock at presentation. We conclude that there is no evidence of oxidant-induced membrane damage manifested by increased plasma levels of CDs or MDA within 2 to 6 hours of blunt injury.