Abstract: A hinge assembly (300) for use in a flat display monitor includes a base seat (10), a support seat (20) and a pivotal mechanism. The pivotal mechanism comprises a pivotal shaft (30) having at least one flat surface (310). The base seat defines a pivotal hole (142) therein. The support seat defines an engaging hole (242). The base seat is rotatable relative to the support seat. The pivotal shaft passes through the pivotal hole of the base seat and the engaging hole of the support seat. One of the base seat and the support seat defines a protrusion (143). The protrusion is substantially V-shaped and has two edges (1432, 1434). The flat surface of the pivotal shaft pivotally engages with the protrusion. Another one of the pivotal hole of the base seat and the engaging hole of the support seat non-rotatably engages with the pivotal shaft.