An adjustable arm rest assembly for use on a chair including a support member, an arm rest member, a locking element and an adjustment member. The support member is attached to the chair and extends substantially upward therefrom. The arm rest member extends substantially coaxially with the support member. The locking element is attached to one of the support member and the arm rest member. A projecting portion extends from an end portion of the locking element and includes a first mating element. The adjustment member is attached to the other of the support member and the arm rest member. The adjustment member and the locking element are movable with respect to one another. A plurality of vertically spaced flanges form a plurality of recesses within the adjustment member. Each recess is sized to receive the projecting portion of the locking element and has a second mating element corresponding to the first mating element. The arm rest member is angularly movable when the first and second mating elements are disengaged. The arm rest member is also angularly and vertically movable when the first and second mating elements are disengaged and the projecting portion of the locking element is disengaged from the recess of the adjustment member.