Brigham and Women's Hospital is converting its financial, administrative and clinical information systems from a mini-computer environment to a platform based on MUMPS and a network of several thousand personal computers. This article describes the project rationale and status and provides an overview of the architecture of the new system. The initial results of the project indicate that the personal computer network can provide large amounts of processor power and storage at costs per unit of power and storage that are several times less expensive than the minicomputer environment. The performance of the converted Accounts Payable system indicates that the architecture can deliver acceptable performance.