Breast cancer (BC) is one of the most common malignancies among women in the world. There is a global attempt to diagnose BC as early as possible. Long noncoding RNAs (lncRNAs) are emerging as novel targets and biomarkers for BC diagnosis and prognosis. Aberrant expression of lncRNAs is associated with BC development, making them a potential tumor marker for BC. To investigate this possibility, we determined the expression levels of Down syndrome cell adhesion molecule‐antisense RNA‐1 (DSCAM‐AS1) and mitotically‐associated long non‐coding RNA (MANCR) lncRNAs in BC tissues. This case–control study included 50 paired tumor and adjacent nontumor tissues from female BC patients. The total RNA was isolated and the expression levels of MANCR and DSCAM‐AS1 lncRNAs were assessed using quantitative real‐time reverse transcription‐PCR. Potential correlations between lncRNA levels and clinicopathological characteristics were also analyzed. DSCAM‐AS1 and MANCR lncRNAs were significantly upregulated in BC tumor tissues compared with the adjacent nontumor tissues. We also found the significant upregulation of DSCAM‐AS1 in advanced tumor–node–metastasis stage (TNM III) of BC tumor tissues. Furthermore, the expression of DSCAM‐AS1 and MANCR in HER‐2 positive patients was significantly higher than HER‐2 negative affected individuals. Receiver operating characteristic curve analysis showed a satisfactory diagnostic efficacy (P value < 0.0001), which means that DSCAM‐AS1 and MANCR lncRNAs can potentially serve as a biomarker. The present study might provide further approval for the clinical diagnostic significance of DSCAM‐AS1 and MANCR lncRNAs that their high expressions were associated with aggressive clinical parameters of BC.