We aimed to determine whether 3-nitropropionic acid (3-NPA) preconditioning protects rat livers against warm ischemia/reperfusion injury. We hypothesized that 3-NPA mediates its protective effects by Bcl-2 upregulation. Brown-Norway rats (200 g) were injected with 3-NPA (10 mg/kg intraperitoneally) 24 h before 90 min of selective warm in situ ischemia. In additional experiments, 30-day survival was studied after 90 min of warm liver ischemia and resection of nonischemic liver tissue. We demonstrate increased mRNA and protein levels of Bcl-2 by real-time polymerase chain reaction, immunohistochemistry, and Western blot analysis in 3-NPA-pretreated rats. All treated animals survived, whereas all untreated rats died within 3 days after selective ischemia and resection of the nonischemic tissue. This corresponded well with a significant decrease of caspases 3 and 9 activity at 1 h of reperfusion after preconditioning with 3-NPA as compared with untreated rats. The histological sections showed protection of liver tissue after 3-NPA by reduction of apoptotic and oncotic tissue damage. Lipid peroxidation in liver tissue was reduced after 3-NPA preconditioning. We show that subtoxic doses of the mitochondrial toxin 3-NPA induces tolerance to warm liver ischemia in rats associated by synthesis of Bcl-2. Bcl-2 upregulation might protect against the postischemic burst of reactive oxygen species and therefore reduces apoptotic- and oncotic-related cell death.