We found that although HDAC1, HDAC2, and HDAC3 all displayed typical oncogenic characteristics in the tumorigenesis and development of breast cancer, only patients with high expression of HDAC3 exhibited earlier occurrence of brain metastasis (BM), and the patients with BM had relatively higher HDAC3 expression than those without BM. The gene discussed is HDAC2; the disease is breast carcinoma.