The main malignant tumor of the bone tissue is represented by osteosarcoma, neoplasia with a reserved prognosis and an unpredictable evolution, often aggressive. Cell cycle disruption is one of the complex biomolecular mechanisms involved in the progression of osteosarcomas. In this study, we analyzed the immunoexpression of Ki67, p53 and cyclin D1 for 18 primitive osteosarcomas in relation to the clinicopathological prognosis parameters of the lesions. The results indicated the predominance of lesions in male young patients, with femoral location, most tumors being represented by the osteoblastic type, with high grade, size <8 cm and in advanced stages. Reactions were present in all cases, the high immunoexpression being associated with osteoblastic∕epithelioid types (Ki67, cyclin D1, p53), high grade (Ki67, cyclin D1) and advanced stage (Ki67, cyclin D1). The study revealed a positive linear relation of the investigated immunomarkers expression, which indicates their usefulness in identifying lesions with aggressive progression potential.