Objective: To evaluate the expression of stanniocalcin-1 (STC-1) and to investigate the correlation of STC-1 with expression of estrogen receptor (ER), progesterone receptor (PR) and clinical parameters, histopathological findings and prognostic factors in endometrioid endometrial cancer (EEC).Materials and Methods: In this retrospective study, STC-1 (cytoplasmic), ER (nuclear), and PR (nuclear) stainings were applied to tissue microarray sections of 89 EEC, 27 endometrial intraepithelial neoplasia (EIN), and 21 normal endometrium (NE). Prognostic factors such as age, tumor size, depth of myometrial invasion, lymphovascular invasion, perineural invasion, and lymph node metastasis were compared with the expression of these markers.Results: ER showed significantly higher positivity in grade 1 EEC. PR expression was also higher in grade 1 EEC, but these findings were not statistically significant. Strong expression of STC-1 was observed in EIN and EECs compared with NE. STC-1 showed low staining in the NE, and high staining was also noted in the EIN foci adjacent to the NE. STC-1 expression was positively correlated with grade 1 EECs. Conclusion: STC-1 expression was positively correlated with low histologic grade in EECs. STC-1 can be used for distinguishing low-grade endometrioid tumors and high-grade endometrioid tumors in curretage specimens. Since STC-1 is related to well differentiated tumors, it can also be regarded as a good prognostic factor in EECs.