It is vital to study the impact of heat since it has an unwanted phenomenon on the operating life of parts produced, which is in turn effect the cost of production. when dimension accuracy is the primary function Wire cut machining comprehensively used specially when machining hard metal by using precisely controlled sparks that occur between a very thin wire and a workpiece in the presence of a dielectric fluid. The aim of this research is to study the effects of some Wire Electrical Discharge Machining (WEDM) variables on heat affected zone, white layer and Surface Roughness (SR) of high speed steel using ANOVA method to analyze the behavior of control parameters such as pulse on time (μs), current and wire tension. Experimental investigations separates into two main parts in the first one the wire electrical discharge machining process was accomplished on smart EDM (Electra wire cut machine), and in the second part the roughness of the machined samples surface was tested and the samples were prepared to be measured. The results shows that the heat affected zone and the white layer are affected with the risen of the current and pulse on time values more than the risen in wire tension values, as well as the wire tension affects the surface roughness more than the current and pulse on time.