Uterine sarcomas are heterogeneous malignancies, both clinically and histologically. The process of oncogenesis depends on gene mutations and uncontrolled mitotic cell division that is promoted by blocking pathways of apoptosis. Caspase 9 and p53 protein play an important role in the process of cell apoptosis. Objectives: The aim of the study was to assess the expression of selected apoptosis proteins (caspase 9 and p53) using immunohistochemistry. Material and methods: A total of 28 tissue samples diagnosed in postoperative histopathological examination as leiomyosarcoma were tested. Twenty eight samples of leiomyomas were used as the control group. Colorful reactions with appropriate antibodies were performed to assess the expression of caspase 9 and p53. From every section 5 fields on view were chosen, in each one 100 cells were assessed using 400x magnification. T-Student parametric test and U Mann-Whitney test were used for statistical analysis. Results: Expression of caspase 9 was significantly lower (p<0.05) in leiomyosarcoma tissues (33.2%) as compared to leiomyomas (60.4%). Expression of p53 protein was significantly lower in leiomyosarcoma tissues than in leiomyomas (30.1% vs. 51.3%, p<0.001). Conclusions: Significantly lower expression of caspase 9 and p53 in leiomyosarcoma tissue samples suggests that impaired deregulation of apoptosis mechanisms plays a role in the development of these tumors.