In Hierarchical Mobile IPv6 (HMIPv6) networks, the mobility anchor point (MAP) is introduced to localize binding update messages destined to the home agent. In a large-scale wireless/mobile network, multiple MAPs may be deployed in order to provide more scalable and robust mobile services. In this case, it is important for a mobile node (MN) to select the most appropriate MAP among them. In this paper, we propose an adaptive MAP selection scheme for HMIPv6 networks. In the adaptive MAP selection scheme, an MN first estimates its session-to-mobility ratio (SMR). Then, based on its SMR, the MN chooses a MAP that minimizes the total cost, consisting of the binding update cost and packet delivery cost. In addition, the MN calculates two threshold SMR values, which adaptively trigger a new MAP selection procedure. If the estimated SMR is larger (or smaller) than the upper (or lower) threshold SMR value, the MN recalculates the total cost and re-selects a MAP that minimizes the total cost. ...