Abstract: A cotter pin which is engageable with a fastening member is formed from a wire and includes a bight with a pair of legs that extend therefrom. Specifically, the bight is formed with shoulders that will substantially conform with a surface of the fastening member. Also, each end of the legs of the cotter pin is formed with a retainer member which has an abutment that will substantially conform with another surface of the fastening member. More specifically, one surface is at one end of an aperture which passes through the fastening member, and the other surface is at the other end of the aperture. Each retainer member is formed with a point at the end of its respective leg, and these points are spaced from each other by a distance which is less than the diameter of the aperture that is formed through the fastening member. For engagement of the cotter pin with the fastening member, the points of the retainer members are positioned at an opening of the aperture.