Here, we show that calycosin inhibited the proliferation of both ER− (MDA-MB-468 and SKBR3) and ER+ breast cancer cells (MCF-7 and T47D) and that these inhibitory effects were associated with the up-regulation of the long non-coding RNA (lncRNA) WDR7-7. This evidence concerns the gene WDR7 and breast carcinoma.