NO is an important mediator in the generalized inflammatory response of the body during sepsis and septic shock. We investigated the possible effects Of L-arginine and aminoguanidine on plasma NO levels and the interaction between NO levels and lung tissue damage and blood gases in sepsis. Fifty Wistar male rats were used in this study and divided into five groups: group 1, sham group; group 2, CLP (sepsis); group 3, CLP + 10 mg/kg L-arginine administration; group 4, CLP +15 mg/kg aminoguanidine administration; group 5: CLP + L-arginine + aminoguanidine given in similar doses. Sepsis was induced by cecal ligation and puncture (CLP) method. Drugs were administered at postoperative hours 4 and 12. The levels in the aminoguanidine and aminoguanidine + L-arginine groups were similar to the sham group. Lung tissue damage in the sepsis and L-arginine groups was more severe than the other groups.