Objectives: Squamous cell carcinoma of the oral cavity (SCCOC) is the fifth most common among malignant tumors, characterized by a high incidence of locoregional recurrence. Since the standard prognostic indicators do not provide reliable information on the biological behavior of the tumor and the possibility of recurrence, the search for new markers that may have prognostic and therapeutic value is needed. Osteopontin (OPN) is a multifunctional protein that has recently been proposed as a prognostic marker in multiple tumor types. It is involved in the interaction of tumor cells and their microenvironment, which plays a key role in the tumor progression and metastasis and is reflected in the morphology of the tumor in the area of invasive tumor front. Tumor associated macrophages are considered to be a key component of the tumor microenvironment, which can have a different impact on the growth and metastasis of tumors. The aim of our study was to determine whether increased expression of osteopontin plays a role in the progression SCCOC's and whether it is related to the morphology of the invasive tumor front. Also, we wanted to examine the prognostic value of the macrophage content in the tumor microenvironment and its relationship to osteopontin expression. Patients and Methods: The study included 86 patients that were surgically treated for SCCOC between 2000 and 2007 at the Department of Maxillofacial and Oral Surgery, Clinical Hospital Center Rijeka. Tumor microaree were stained by immunohistochemical methods using antibodies that recognize OPN, Ki67 proliferation marker, and CD68 macrophage marker, and analyzed by using a computer program. Expression of osteopontin and macrophage content in the tumor were compared with the standard prognostic parameters and survival of patients, as well as with the Ki67 proliferative index. The whole tumor-tissue sections, stained with hemalaun-eosin, were evaluated for the invasive tumor front grade (GITF) and compared with the clinicopathological parameters and osteopontin expression. Results: The expression of OPN in tumor cells (t-OPN) was significantly higher compared to normal oral mucosa (p<0.001). Increase in the t-OPN expression was followed by the increased OPN expression in the stromal compartment of the tumor (s-OPN) (p=0.023), and associated with higher N stage (p=0.045), and TNM stage (p=0.033). Higher GITF was associated with higher N stage (p=0.006) and TNM stage (p=0.025), and a higher t-OPN expression in the superficial part of the tumor (p=0.038). In univariate analysis higher t-OPN expression (p=0.022) and a higher GITF (p=0.003) were associated with shorter survival of patients. In multivariate analysis, by comparing with standard prognostic factors, t-OPN expression was independent predictive factor for survival (p=0.048). When the GITF was included, t-OPN lost the status of an independent predictor (p=0.085), while GITF gained the status (p<0.001). Expression of t-OPN was not associated with traditional histological grade (p=0.260), Ki67 proliferative index (p=0.145) nor with the macrophage content in the tumor (p=0.904). Expression of the s-OPN and macrophage content in the tumor were not associated with prognostic parameters and survival of patients. Patients with combined high t-OPN expression and the high macrophage content in the tumor lived significantly shorter than those with low individual or both parameters (p=0.014). Conclusion: Increased OPN expression as a single parameter or associated with a high macrophage content can serve as a predicting factor of poor prognosis, and shorter survival in patients with SCCOC. ITF grade also predicts the course of the disease and has a better prognostic value compared to traditional histological grade. Determination of these parameters in pathohistological diagnosis of squamous cell carcinoma of the oral cavity allows the identification of patients at high risk for relapse which would benefit from additional treatment methods.