Aim: Gastrin releasing peptide (GRPR) and αvβ3 integrin receptors are known to be expressed in primary breast tumor tissue and metastatic tissue. There is a limited number of studies on the potential role of these receptors in molecular imaging. Aim of this study was to investigate the relationship between these receptors in cancerous tissues and their F-18 florodeoksiglukoz (FDG) positron emission tomography (PET/CT) parameters in histopathological and immunohistochemical subtypes of breast cancer. Method: In this prospective study, the presence and level of GRPR and integrin αvβ3 receptors, in 90 tumor tissues of 87 breast cancer patients whose preoperative staging F-18 FDG PET/CT examinations performed between 2012-2018, were analyzed. Immunohistochemical scoring of GRPR and integrin αvβ3 receptors was performed as follows; none: 0, weak: 1, medium: 2 and strong: 3. According to the integrin αvβ3 receptor status, integrin αvβ3 score were divided to two groups as 0 (negative) and 1-2-3 (positive). In addition, the presence of ER, PR, Her-2 receptor obtained from breast tissue, GRPR and integrin αvβ3 receptor presence and level, ki 67%, histopathological subtypes were compared with the PET/CT findings like tumor size, axillary lymph node involvement, distal nodal metastasis, and presence of organ metastasis and F-18 FDG SUVmax of primary tumor. Results: F-18 FDG involvement was observed in all of the 90 malignant breast lesions in PET/CT imaging. In the 75/90 breast tumor tissue, GRPR expression and 22/90 tissue integrin αvβ3 expression have been detected. In 6 tissues, both GRPR and integrin αvβ3 receptors were not detected. The relationships between primary tumors' SUVmax value and GRPR score 0,1,2 and 3 groups were presented Table1 and integrin αvβ3 score 0 and score 1-2-3 groups were presented in Table 2. Conclusion: Although there was no statistically significant relationship between the GRPR score of 0,1,2,3 and the mean F-18 FDG SUVmax of the primary tumor, a negative trend was detected between the state of GRPR and the primary tumor F-18 FDG SUVmax. No statistically significant difference was found between the mean values of F-18 FDG SUVmax of integrin αvβ3 score 0 and score 1-2-3 tissues (p>0.05). However, the high incidence and level of GRPR receptor positivity in breast cancer tissue suggests that this receptor may have potential role in molecular imaging and radionuclide therapy. [ABSTRACT FROM AUTHOR]