GLI proteins are transcriptional factors which act as of Hedgehog signal pathaway mediators. Current research link the occurence of many carcinomas with aberrant activity of the Hedgehog signal pathway. Among these are breast cancer, rhabdiomiosarcoma, colorectal cancer, pancreatic cancer and glioblastoma. The goal of this study was to examine the expression of GLI1 and GLI3 proteins in both high and low grade serous ovarian carcinomas using indirect immunohistochemistry. Tissue samples of high and low grade serous ovarian carcinomas were collected as well as samples of healthy ovarian tissue which represented control. The results of immunohistochemistry were quantified using the stereological variable of volumetric densitiy (Vv, mm0) and were statistically analyzed. Results showed a statistcally significant higher expression level of GLI1 and GLI3 in low grade serous carcinoma than in healthy ovarian tissue, while statisticallly significant difference of expression level in high grade serous ovarian carcinoma was in comparison to healthy ovarian tissue was not found. Furthermore, a statistically significant higher expression level of GLI1 and GLI3 in low grade serous ovarian carcinoma than in high grade serous ovarian carcinoma was obtained. Examining the nuclear expression level, a statistically significant higher expression level of GLI3 in the cell nuclei of low and high grade serous ovarian carcinoma than in the cell nuclei of healthy ovarian tissue was found. Moreover, a statistically significant higher expression level of GLI3 in relation to GLI1 expression level in both low and high grade serous ovarian carcinoma , healthy ovarian tissue and cell nuclei low grade serous carcinoma nuclei was reported. Results of this research emphasize the significant role of Hedgehog signal pathway in the development of serous ovarian carcinoma. Moreover, further research could not only more closely clarify the role of GLI proteins in carcinogenesis but also enabled their use in diagnostics and therapy.