Endometrial cancer is the most common gynecological malignancy in Croatia. The aim of this study was to determine the immunohistochemical expression of estrogen receptors (ER) and progesterone receptors (PGR) in cancer cells and in the myometrium and to correlate it with prognostic factors of endometrial carcinoma. ER positivity in carcinoma cell nuclei was found in 42 cases (73.7%) and PGR positivity was found in 39 cases (68.4%). Loss of ER in carcinoma cell nuclei correlated with larger tumor size (p = 0.041), poor carcinoma differentiation (p = 0.012), a more aggressive histological type (p < 0.001), lymphovascular space invasion (p = 0.002) and a higher surgical stage (p = 0.037). Loss of PGR in carcinoma cell nuclei correlated with an increased age in patients (p = 0.009), poor tumor differentiation (p = 0.002), a more aggressive histological type (p < 0.001), lymphovascular space invasion (p = 0.002) and a higher surgical stage (p < 0.001). The lower expression of both receptors did not correlate with the depth of myometrial invasion. Regarding the status of receptors in the myometrium, loss of PGR in the myometrium correlated with a more aggressive histological type (p = 0.005) and a lack of ER in the myometrium tended to correlate with tumor growth (p = 0.059). In conclusion, the loss of both hormone receptors in carcinoma cells and loss of PGR in the myometrium was a predictor of a more aggressive type of endometrial cancer and a poor prognosis.