Abstract: Mastitis is a common disease of lactating cows and is caused by several different types of bacteria including Nocardia farcinica. The objective of the current study is to demonstrate pathology clinical manifestations of experimental mastitis in dairy cows induced by field isolates of Nocardia farcinica. The infection was done by intramammary infusion in two healthy lactating dairy cows using two field isolates of N. farcinica. The infected animals were examined periodically for clinical signs and laboratory profiles. The first cow showed typical clinical signs of acute Nocardia mastitis with granulomatous reaction whereas the second cow showed sub-acute clinical mastitis. While the first cow died within a few days post infection, the second cow survived but didn’t respond to standard mastitis treatment. Treatments of the experimentally induced mastitis with Neomastipra® and Gentamast® failed to cure the infection and after the withdrawal period of both drugs Nocardia continued to shed from udder. Clinical isolate of Nocardia farcinica caused mastitis that was either subacute/irresponsive to treatment or fatal peracute leading to death.