Abstract: An end milling process is widely used in fabrication of complex contours and shape parts at high spindle speeds. Many researchers try to investigate one of important aspect, which come across during machining is the self exited chatter vibration which causes severe damage of the tool and quality of the machined surface. The present work is focused on the Magneto-Rheological Damping effect on stability of chatter in an end milling process during machining. The end mill cutter was modeled as a rotating Euler Beam with an attached MR Damper as bar element and its first five modes of vibrations are considered. The stability analysis has been carried out by considering the two degrees of freedom of the model.