A simple model, called the direction restriction model, for developing partially adaptive routing algorithms for n.dimensional meshes is introduced in this paper. This model is based on dividing a system into two unidirectional networks that contain all physical channels of the system. Delivery of a message is broken into two phases. In the first phase, a message is routed adapiively to an intermediate node using one unidirectional network. In the second phase, the message is routed adaptively to its destination in the remaining network. Messages are routed by using the wormhole switching paradigm. All of the algorithms that are developed by using this model are proven to be deadlock free at no extra cost »w terms of virtual channels. Routing algorithms are developed for 2-dimensional meshes, 3-dimensional meshes, and hy-percubes. The effectiveness of these algorithms for different traffic patterns is evaluated via simulation. The ease of use and simplicity of the direction restriction model make it an attractive tool for developing partially adaptive routing algorithms for n-dimensional meshes.