Background: Angiogenesis is essential for the growth, invasion and metastasis of solid tumors. Research on related factors such as microvessel density can be helpful in predicting a tumor's behavior. CD105 has been introduced as a marker of angiogenesis which stains vessels that are in the proliferating stage. There are some controversies about the relation of microvessel density and clinicopathological features of oral squamous cell carcinoma. The aim of this study is to determine the CD105 expression in oral squamous cell carcinoma and its relation to the clinicopathological features of this disease.Methods: We studied a total of 42 patients who had oral squamous cell carcinoma. The control group consisted of 15 cases with normal oral epithelium. CD105 immunostaining was performed on 4 μm thick tissue sections. Intratumoral and peritumoral microvessel density in ten areas of the sections were recorded by two pathologists.Results: There was a significantly higher CD105 microvessel density value in the tumoral tissues compared with normal tissues. In addition, there was more expression of this marker in the invasive front area. The CD105 microvessel density value had a positive relation with lymph node metastasis. There was an association between tumor size and CD105 microvessel density in the invasive front region. A negative association between tumor grade and CD105 microvessel density value in the intratumoral region was observed. In both areas, CD105 expression was higher in cases with advanced clinical stage. There was no association between this marker and patients' ages or gender.Conclusion: CD105 microvessel density can be a useful factor for predicting the course of oral squamous cell carcinoma.