Objective(s): Breast cancer is the second leading cause of cancer death in females. Understanding molecular mechanisms in cancer cells compared with normal cells is crucial for diagnostic and therapeutic strategies. Long intergenic non-protein coding RNA, a regulator of reprogramming (lincRNA-RoR) is a noncoding RNA which initially was detected in induced pluripotent stem cells, and it has an important role in cell reprogramming and highly expressed in breast cancer cells. A key point in successful gene silencing is the usage of siRNA delivery system that is safe and efficient. Materials and Methods: In this study, the fifth-generation of PAMAM dendrimer is used as a nanocarrier for entering siRNA molecules for gene silencing of lincRNA-RoR. WDR7 is the gene encoding adjacent of lincRNA-RoR, which has an important role in apoptosis and cell cycle. Gel retardation assay was used to find the best Negative/Positive (N/P) molar charge ratio of siRNA- PAMAM transfected into MDA-MB 231 cells. MTT assay was performed 24 hr after transfection revealed the IC50 value (half maximal inhibitory concentrations) about 100 nanomolar for lincRNA-ROR siRNA.Results: The lincRNA-RoR and WDR7 gene expression changes were evaluated by real-time PCR after siRNA treatment and showed an increase in the gene expression of WDR7. Conclusion: This study showed that PAMAM dendrimer G5/ siRNA could be a useful system delivery for future gene therapy approaches.