Alterations in the antioxidative system have been observed during total parenteral nutrition (TPN). Light exposure or changes in the composition of TPN formulas may affect this system. Bacterial translocation (BT) is frequent under TPN and may be related to oxidative status. The aim of this study was to determine the adverse effects of standard and glutamine-enriched TPN, with or without light exposure, on oxidative status (liver and kidney-reduced glutathione, GSH) and its relationship to BT. Thirty-three adult Wistar rats underwent central-venous cannulation and were randomly assigned to one of four groups receiving different TPN regimes for 10 days. The TPN group (n = 10) had standard TPN, the TPN(-) group (n = 8) standard TPN without light exposure, the GTPN group (n = 8) glutamine-enriched TPN, and the GTPN(-) group (n = 7) glutamine-enriched TPN without light exposure. A sham group (n = 16) receiving chow and water ad libitum and saline i.v. served as controls. At the end of the experiment, GSH was determined in liver and kidney tissue. Mesenteric lymph nodes and peripheral and portal blood samples were cultured for BT. Compared to sham rats, TPN groups had statistically significant lower GSH levels, but there were no differences between standard or glutamine-enriched groups or light-exposure groups. Sham animals had 12% BT. Significantly higher BT (P < 0.05) occurred in TPN rats: 70% in the TPN group, 88% in the TPN(-) group, 86% in GTPN (-) animals, and only 50% in the GTPN group (P = 0.06 vs TPN group). In conclusion, (1) TPN reduces antioxidant capacity; (2) glutamine supplementation or light protection does not improve tissue antioxidant capacity under TPN; (3) the absence of light exposure does not improve TPN-related BT; and (4) glutamine supplementation tends to reduce BT only in the presence of light.