The G-protein-coupled-receptor 30 (GPR30) is a new membrane estrogen receptor. The aim of the present study was to determine the correlations among GPR30, ERα, PR, C-erbB-2, p53, TNM stage, and pathologic grade in breast carcinomas. Two hundred forty-one biopsy specimens were evaluated with immunohistochemical assays, and then correlations were analyzed. Low negative correlations of GPR30 with ERα (r = −0.144, P<0.05) and PR (r = −0.214, P<0.01) were observed. Associations of GPR30 with C-erbB-2, p53, TNM stage, and pathologic grade were not confirmed. These findings indicated that GPR30 might be an independent prognostic factor in breast carcinomas.