Mastitis is a major economic concern for the dairy industry. Conditions such as parturition cause a transient immunosuppression that leads to increased incidence of mastitis. One facet of periparturient immunosuppression is a functional impairment of the blood and milk neutrophils in dairy cows. To better understand the biology of the bovine neutrophil we report the first proteomic analysis of the bovine neutrophil. We have identified over 250 proteins using one-dimensional electrophoresis followed by reverse-phase chromatography in line with electrospray tandem mass spectrometry. A large number of metabolic proteins were identified, including most of the enzymes required for generation of NADPH and ATP. In addition, many proteins were identified that participate in cell mobility and phagocytosis. All the bovine members of the cathelicidin family were identified, as well as other proteins with immunological functions. Proteins important for cell signaling, vesicular transport, control of apoptosis and other functions were identified giving an overview of the bovine neutrophil proteome.