Wire electrical discharge machining WEDM is one of the major non –traditional machining processes the application of WEDM has increased since 1970s', it has many application in the machining of conductive materials for production of aero space/ air craft, die/mold and medical parts ,this is due to high machining productivity, dimensional accuracy and surface quality ,in this study medium carbon steel 33 was machined by WEDM ,the experimental study determined the effect of pulse on time, pulse off time, servo feed rate on machined surface finish and material removal rate .the selected ranges of pulse on time ,pulse off time, servo feed rate were 8-11-14 sec,10-14-16 sec,2-3-5 mm/min respectively ,the results of present study determined that the most influential machining parameter on surface roughness was pulse on time, other parameters were less effective and the nearly only influential machining parameter on material removal rate was servo feed rate in the WEDM using brass wire of 0.25 mm.