Background <p>Several lines of evidence strongly suggest that circular RNAs (circRNAs), a novel class of single-stranded covalently closed non-coding RNAs, are implicated in the etiology of a variety of human diseases, including cancer. We aimed to quantify the expression levels of circ_0002301 and circ_0001955 in breast tumor and normal tissues adjacent to the tumor (NAT).</p> Materials and methods <p>Breast tumor and paired NAT samples were freshly collected following surgery from fifty women diagnosed with breast cancer. After total RNA extraction, the expression levels of circ_0002301 and circ_0001955 were assessed using quantitative real-time polymerase chain reaction (qPCR) technique. The correlation between circ_0002301 and circ_0001955 expression levels and clinicopathological features evaluated using Spearman’s correlation coefficient. Receiver operating characteristic (ROC) curve was drawn to determine the diagnostic values of the studied circRNAs.</p> Results <p>We found that circ_0002301 expression level was significantly up-regulated in breast tumor compared to NAT (fold change = 3.39, <i>P</i> = 0.0001). The expression level of circ_0001955 in breast tumor was significantly higher than that in NAT(FC = 2.214, <i>P</i> = 0.009). No significant correlation was between the expression levels of circ_0002301 and circ_0001955 in breast tumor (<i>r</i> = 0.269, <i>P</i> = 0.059). The ROC analysis revealed that the area under the curve (AUC) values of circ_0002301 and circ_0001955 were 0.660 and 0.650, respectively.</p> Conclusion <p>The present study provides evidence that up-regulation of circ_0002301 and circ_0001955 may be associated with breast cancer tissues.</p>