Journal of Research in Medical Sciences1735-199511220060525Immunohistochemical Assessment of Natural Killer cells in normal and inflamed Dental Pulps119121ENSBMousaviDep. of Endodontics, Isfahan University of Medical Sciences. sbmousavi2@yahoo.comATalebiSKianoosh2006072220060722Introduction: Immunohistological studies have shown the pulpal responses to bacteria and their product’s inflammation, but presence of natural killer (NK) cells were unclear. This study detected NK cells in normal and inflamed pulps. Methods: From the third molars, 15 normal and 15 inflamed pulps were extirpated out and studied by indirect immune peroxides technique and microscope for NK cells. Results: We did not find NK cells in normal coronal pulps, but they were detected in one third of inflamed coronal pulps. Conclusion: NK cells are absent in normal coronal pulps and present in the intensively inflamed pulps. They may play a role in the pathogenesis of pulp lesion. Key Words: Immunohistological, Inflamed pulp, Natural killer cells, Antibody, Inflammation