Abstract: Adherence and invasion of Klebsiella pneumoniae to bovine mammary epithelial cells can be the potentially pathogenic mechanisms. In the present study, the cultured bovine mamary epithelial cells was applied to detect the adherence and invasion of Klebsiella pneumoniae. The cells were determined by immunohistochemistry with anti-cytokeratin antibody and transmission electron microscopy. Positive immuno-reaction and desmosomes were observed respectively. Klebsiella pneumoniae, originating from clinical bovine mastitis cases, Salmonella typhimurium and Escherichia coli DH5α were tested for their ability of adherence and invasion to bovine mammary epithelial cells in vitro Results showed that Klebsiella pneumoniae adhered to bovine mammary epithelial cells in dose and time dependent until saturation, and invaded the cells without attenuation. In addition, no significant influence on the bacteria viability in cells was observed during the experimental time. The results of the present paper may partially contribute to an understanding of the pathogenesis of Klebsiella pneumoniae mastitis by surviving in the cells to protect themselves from antimicrobial drugs and host defense system.