The objective of this paper is to obtain the optimal parameters of the helical gear in order to eliminate the gear failure due to pitting and scuffing using Taguchi method. The investigation is done with the help of the transmission department in an automobile industry. During the investigation, the various defects that causes the gear failures are studied. The process parameters considered for the study are module, pressure angle and material at two levels. To obtain the optimal process parameter combination, optimization is carried out by DOE method.