Introduction: Idiopathic granulomatous mastitis (IGM) is a rare benign inflammatory breast disease that can clinically and radiographically mimic breast carcinoma and bacterial mastitis. The aim of this study is to investigate the importance of levels of the inflammation markers, interleukin-33 (IL-33), soluble ST2 receptor of IL-33 (sST2), procalcitonin (PCT), and CRP on differential diagnosis of IGM and breast cancer (BC). Methods: 25 patients with IGM and 32 patients with primary BC who applied to General Surgery Clinic, and 30 healthy volunteer women with similar demographic condition were enrolled in the study. While the IL-33, sST2, and PCT levels were measured with ELISA method, other biochemical parameters were studied with autoanalyzer. Results: IL-33, sST2 levels were significantly higher in both BC and IGM groups than in control (p < 0.001). More importantly, the IL-33 levels of IGM group were found to be significantly higher when compared to the group with BC (p < 0.001). Accordingly the sST2 levels of the patients with IGM were significantly lower than the patients with BC (p < 0.001). There was no statistical significance between PCT levels BC and IGM groups (p > 0.05). Conclusion: The results of our study suggest that measurement of IL-33 and its receptor sST2 levels, alongside radiological studies can help distinguishing IGM from BC. Findings of our study need to be supported with additional studies.