Statement and Problems: Oral malignant tumors are the eleventh most common malignancy in the world, the most common type of which is oral squamous cell carcinoma (OSCC).  It is typically seen in middle-aged to elderly men but it has recently been seen in young adults.Purpose: The aim of this study was to determine the prevalence of oral squamous cell carcinoma in two different age groups in an Iranian population, and also to compare the related factors in these two groups.Materials and Method: The study was descriptive and performed In Imam Khomeiny Cancer Institute, Taleghani and BooAli hospital in Tehran during Apr 2007 to July 2009. Our study group consisted of patients diagnosed with OSCC after biopsy. All demographic data, stage of the disease, occupation, blood group and other risk factors were gathered by reviewing pathological and clinical records. The patients were divided into younger (≤45) and older (>45) age groups and related factors in these groups were compared through Chi-square test in SPSS statistical package (16).Results: Out of 170 patients suffering from OSCC, 138 cases (81.2%) were in the older age group.  In this group, there were no statistically significant differences between sex. Tongue and blood group A were the most common site and blood group, respectively ( p <0.05). Thirty two patients (18.8%) were in the young group, and mandibular mucosa and floor of the mouth were the most affected site. The great number of the patients were from the north of the country and in stage (IV) of the disease ( p <0.05).Conclusion: Oral squamous cell carcinoma is more prevalent in older Iranian patients and the pattern of the disease is different in young patients.Key words: Oral squamous cell carcinoma, Young and old patients, prevalence, Iranian population