An important issue in the design of a mobile computing system is how to manage the location information of mobile clients. In the existing commercial cellular mobile computing systems, a two-tier architecture is adopted. However, the two-tier architecture is not scalable. In the literatures, a hierarchical database structure is proposed in which the location information of mobile clients within a cell is managed by the location database responsible for the cell. The location databases of different cells are organized into a tree-like structure to facilitate the search of mobile clients. This architecture can distribute the workload amongst the location databases in the system. The location database organization has much impact on the total location management cost. However, non of previous work touches upon this problem. In this paper, considering the mobility patterns of mobile clients in different cells, we give a heuristic algorithm to cluster the location databases with the objective to reduce the location management cost. Extensive experiments are designed to evaluate the performance. The comparison shows that our location database clustering method can result in location update cost reduction.