Zileuton sodium (A 64077 sodium) is a potent and selective inhibitor of 5-lipoxygenase, exhibiting inflammatory activities. In anti-CD3-treated cells, IL-2 decreases in Zileuton sodium (A 64077 sodium)-treated and untreated cells with increasing incubation time. Zileuton sodium (A 64077 sodium) likely reduces IL-2 levels by inhibiting 5-lipoxygenase, hence leukotriene B4 production, an IL-2 inducer. In Zileuton sodium (A 64077 sodium) (5 mg/kg, p.o.) treated I/R rat, the effect of Zileuton to decrease NF-κB expression does not change significantly in the presence of COX inhibitors, and the group reveals significantly lower level of NF-κB staining. Zileuton (5 mg/kg, p.o.) treatment given to I/R rats decreases apoptotic index significantly. Zileuton has no significant effect on increased serum TNF-α levels in I/R group. Zileuton sodium (A 64077 sodium) (1200 mg/kg) inhibits the polyp formation in APCΔ468 colon and small intestine. Zileuton treatment inhibits the proliferation rates of non epithelial cells in polyps, and increases the apoptosis rates in polyps in rat. There is significant increase in the number of apoptotic cells in the Zileuton-treated cells both in small intestine and in the colon. The reduced proliferation rate may significantly contribute to the reduction of polyposis in both the small intestine and colon of Zileuton-fed APCΔ468 mice.