Electronic health records (EHR) and electronic billing systems have been proposed as mechanisms to help curb the rising costs of health care in the United States. Given this scenario, our research efforts have targeted the idea of using open-source cloud computing technologies as the mechanism to build an affordable, secure, and scalable platform that supports billing as well as EHR operations. We call this platform MedBook, and in this paper we present the architecture and implementation status of this system. MedBook provides patients, health care providers, and health care payers a platform for exchange of information about EHR, billing activities, and benefits inquiries. MedBook is a Software-as-a-Service (SaaS) application built on top of open source technologies and running on an Infrastructure-as-a-Service platform. The client applications are mobile apps run from iPhone and iPad devices.