This paper introduces a method for rough machining of turbine blades with CNC electrical discharge machining (EDM), which is similar to mechanical milling geometrically and is also modelled by intersections between a cylindrical tool and the workpiece. However, special factors such as DC arcing, electrode wear, and discharging gap compensation have to be considered in the process. These special factors are analysed, and a CAM system catering to four-axis CNC EDM rough machining of turbine blades with a cylindrical electrode is introduced. The tool path generation algorithm has been integrated in an industrial CAD/CAM system (Unigraphics). In addition to machining simulations, real cutting experiments are presented.