en Dentistry Dentistry Original Research Original Research <p> <strong> Background </strong>:Cell proliferation is one of the most critical factors in metastasis and prognosis of the malignant tumors.Recent investigations show that the eosinophil granolosytes have an important role in developing of malignant tumors. The relation between cell proliferation and eosinophilic infiltration in oral squamous cell carcinoma (OSCS) with prognosis is unclear.The aim of this study was to investigate the relationship between the Ki67 expression and eosinophilic infiltration with the clinical features on OSCC. </p><p> <strong> Methods </strong>: This study was cross sectional in which 24 paraffinedembeded block of OSCC selected from the Imam Khomeini hospital cancer institute’s archive. 4 micron sections were prepared and studied for Ki67 antigen immunohistochemically. The labeling index (LI: positive epithelial cells/1000 epithelial cells) of Ki67 positive cells were obtained. In each section eosinophilic cells were counted in 10 fields with 400 (HPF). The relations between the eosinophil cells and Ki67 positive cells counts with clinical features and histopathological differentiation were achived by the linear regression and spirman statistical tests. </p><p> <strong> Results </strong>: There were no any significant relationship between gender, histopathological differentiation and the number of eosinophils and Ki67 positive cells counts (p=0.33 and p=0.73). A significant relationship between lymph node involvement and the number of eosinophils and the Ki67 positive cells counts was found (p=0.04).There was a positive relationship between the number of Ki67 positive cells and the number of eosinophil cells (p=0.05). </p><p> <strong> Conclusion </strong>: A significant relationship between lymph node involvement with eosinophilc cells and Ki67 positive cells counts were exist. </p><p>  </p> Eosinophil cells, Lymph node involvement, Oral squamus cell carcinoma, Ki67 antigen. 758 764 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-742&slc_lang=en&sid=1 Noushin Jalayer Naderi jalayer@shahed.ac.ir 200319475328460013711 200319475328460013711 Yes Oral and Maxillofacial Pathology Department, Faculty of Dentistry, Shahed University, Tehran, Iran. Farrokh Tirgari hosp_cancer@tums.ac.ir 200319475328460013712 200319475328460013712 No Cancer institute, Tehran University of Medical Sciences, Tehran, Iran Mohammad Javad Kharazi Fard mj_khf@yahoo.com 200319475328460013713 200319475328460013713 No Dental Research Center, Tehran University of Medical Sciences, Tehran, Iran. Fateme Farahani Parsa Fateme_fp@yahoo.com 200319475328460013714 200319475328460013714 No Shahed University,Tehran, Iran.