Healthcare information systems are complex and critical enterprise systems that link together geographically distributed hospitals, clinics, physician offices and other business units with distinct business functions and mutual dependencies. In the past, these systems were built based on proprietary solutions, acquired in piecemeal fashion and tightly coupled through ad hoc means. This resulted in stovepipe systems that have many duplicated functions and are monolithic, non-extensible and non-interoperable. How to migrate from these stovepipe systems to the next generation open healthcare information systems that are interoperable, extensible and maintainable is increasingly a pressing problem for the healthcare industry. In this paper, we present our experience in addressing the problem using an architecture-centered approach for enterprise system development and integration based on distributed object technology standard OMA/CORBA. Our case study is conducted from a user organization (as opposed to developer organization) point of view and is based on a large-scale effort undertaken at the Baptist Health Systems of South Florida, a large healthcare organization serving the South Florida region. Key lessons learnt from this case study include: (1) establishing clear architectural vision is essential to successful enterprise system development; (2) adoption of standard architecture and infrastructure is the best approach to achieve interoperable, extensible and cohesive enterprise systems; and (3) an effective development methodology and business process are key to implement the architectural vision.