Long non-coding RNAs (lncRNAs) are newly introduced as tumor-related molecules. They are being considered as potential diagnostic and therapeutic targets in cancer studies. Here, we have assessed the importance of CYTOR (linc00152) as a biomarker for the detection of breast cancer in both tumoral tissue and plasma. The relative expression of breast cancer-associated CYTOR was measured in 20 tumoral and paired margin tissues, and moreover, in 80 plasma samples by real-time-polymerase chain reaction. In addition, plasma levels of CA 15-3 were measured using the ELISA test. The receiver operating characteristic curve (ROC) was applied for assessing the sensitivity and specificity of tested biomarkers. The results of the present study disclosed significantly increases in the CYTOR expression levels in tumor tissue with relative quantitation (RQ) equals to 5.15 (P<0.001) and in plasma (RQ =3.03, P<0.01) of breast cancer patients. The area under the ROC curve (AUC) of circulating CYTOR was 0.907 (95% CI: 0.842-0.972, P<0.001), while it was 0.868 (95% CI: 0.783–0.952, P<0.001) for CA 15-3. Based on these findings, we suggest lncRNA CYTOR as a new potential biomarker for breast cancer detection in both solid tumor tissue and plasma.