Objective: In vitro model of hydrogen peroxide induced apoptosis of SW 480 cells was used to investigate the role of NF κB in the pathogenesis of reactive oxygen species induced apoptosis of intestinal epithelial cells. Methods: Ultra structural changes were observed. Apoptosis of SW 480 cell line was determined by Annexin V and PI double stained flow cytometry. Nuclear translocation of NF κB was determined by anti NF κB polyclonal antibody and EB double staining. NF κB activity was studied by electrophoretic mobility shift assays. RT PCR was performed to study expression of NF κB mRNA. Results: Hydrogen peroxide led to apoptosis of SW 480 cells, condensed or semilunar chromatin even apoptotic bodies could be observed. Nuclear translocation of NF κB, increase of NF κB activity and expression of NF κB mRNA were found simultaneously. Conclusions: Early activation of NF κ B may be one of the mechanisms of apoptosis in intestinal epithelial cells by reactive oxygen species. Objective: In vitro model of hydrogen peroxide induced apoptosis of SW 480 cells was used to investigate the role of NF-κB in the pathogenesis of reactive oxygen species induced apoptosis of intestinal epithelial cells. Methods: Ultra structural changes were observed. Apoptosis of SW 480 cell line was determined by Annexin V and PI double stained flow cytometry. Nuclear translocation of NF κB was determined by anti NF κB polyclonal antibody and EB double staining. NF κB activity was studied by electrophoretic mobility shift assays. RT PCR was performed to study expression of NF κB mRNA NF-κB, NF κB activity, NF κB mRNA increase, NF κB activity, and NF κB mRNA were detected. Conclusions: Early activation of NF κ B may be one of the mechanisms of apoptosis in intestinal epithelial cells by react ive oxygen species.