Summary: Machining parameters such as speed, feed and depth of cut play an important role in determining the residual stress as well as the surface roughness of any material. The material used for the present study is a nickel based superalloy Udimet 720. The alloy finds applications for the manufacture of gas turbine engine components like shafts, discs and blades. Specimens extracted from a test forging of this alloy were machined by milling using different combinations of milling parameters (speed, feed and depth of cut). Residual stress and surface roughness measured on the specimens showed different magnitudes for different combinations of milling parameters. The variations did not reveal any definite trend with respect to milling parameters. In several cases the increase in the magnitudes of residual stress and surface roughness could be attributed to different degrees surface working undergone by the specimens during the milling operation. Analytical relationships were developed between the magnitudes of residual stress and surface roughness and milling parameters. Experimental and analytical data suggested that the combined effects of milling parameters influence both residual stress and surface roughness. Key words: Residual stress, surface roughness and machining parameters Corresponding Author: Dr.BR Sridhar Phone: 91-080-25040337, Fax:91-080-25241507, E mail:sridharbr@mail.gtre.org