Reperfusion injury following hemorrhagic shock is accompanied by the development of a systemic inflammatory state that may lead to organ failure. Insulin connecting peptide (C-peptide) has been shown to exert anti-inflammatory effects in sepsis and myocardial ischemia-reperfusion injury and to ameliorate renal dysfunction in diabetic animals. Hence, we investigated the effect of C-peptide on kidney injury after hemorrhagic shock. We hypothesized that C-peptide would exert renoprotective effects by blunting inflammation. Hemorrhagic shock was induced in male rats (3-4 months old) by withdrawing blood from the femoral artery to a mean arterial pressure of 50 mmHg. Animals were kept in shock for 3 h, at which time they were rapidly resuscitated by returning their shed blood. At the time of resuscitation and every hour thereafter, one group of animals received C-peptide (280 nmol/kg), whereas another group received vehicle. Hemorrhagic shock resulted in significant rise in plasma levels of creatinine and elevated kidney neutrophil infiltration as evaluated by myeloperoxidase activity in vehicle-treated rats in comparison with sham rats, thus suggesting kidney injury. Treatment with C-peptide significantly attenuated the rise in creatinine and kidney myeloperoxidase activity when compared with vehicle group. At a molecular level, these effects of C-peptide were associated with reduced expression of the c-Fos subunit and reduced activation of the proinflammatory kinases, extracellular signal-regulated kinase 1/2 (ERK 1/2), and c-Jun N-terminal kinase and subsequently reduced DNA binding of activator protein 1 in the kidney. Thus, our data suggest that C-peptide may exert renoprotective effects after hemorrhagic shock by modulating activator protein 1 signaling.