Gears are one of the most critical components in mechanical power transmission systems. Thernbending and surface strength of the gear tooth are considered to be one of the main contributors forrnthe failure of the gear in a gear set. Thus, analysis of stresses has become popular as an area ofrnresearch on gears to minimize or to reduce the failures and for optimal design of gears. This thesisrninvestigates the characteristics of an involute helical gear system mainly focused on bending andrncontact stresses using analytical and finite element analysis.rnTo estimate the bending stress, three-dimensional solid models for different number of teeth arerngenerated by Pro/Engineer that is a powerful and modern solid modeling software and the numericalrnsolution is done by ANSYS, which is a finite element analysis package. The analytical investigationrnis based on Lewis stress formula.rnThis thesis also considers the study of contact stresses induced between two gears. Present methodrnof calculating gear contact stress uses Hertz's equation. To determine the contact stresses betweenrntwo mating gears the analysis is carried out on the equivalent contacting cylinders. The resultsrnobtained from ANSYS are presented and compared with theoretical values.rnFace width and helix angle are important geometrical parameters in determining the state of stressesrnduring the design of gears. Thus, in this work a parametric study is conducted by varying the facernwidth and helix angle to study their effect on the bending stress of helical gear.