In recent years, materials with unique metallurgical properties such as Inconel-718 have been developed to meet the demands of extreme applications. In this paper an experimental investigation has been carried out to study the influence of various parameters like peak current, pulse-on time and dielectric flushing pressure on EDM deep-hole drilling of Inconel-718. Copper tube of external diameter 2.5 mm and internal diameter 1 mm was selected as the tool electrode which provides flow of dielectric through the electrode, thereby making the process of flushing less critical. Moreover, the performance of machining is evaluated in terms of material removal rate (MRR), electrode wear ratio (EWR) and overcut. Optical microscope was used to judge the quality at the rim of the drilled holes. Peak current, pulse-on time and flushing pressure were found to be the most critical parameters in EDM deep-hole drilling of Inconel-718.