We found that EZH2 expression in breast carcinoma was significantly associated with tumor cell proliferation: 87.3 % (69/79) of breast carcinoma with high Ki67 index (>30 %) showed high EZH2 levels, whereas only 25.7 % (19/74) invasive breast carcinoma with a low Ki67 index (<14 %) showed EZH2 overexpression. The gene discussed is EZH2; the disease is breast carcinoma.