The reference model presented in this chapter encourages the breakdown of m-health systems into the following five key dimensions: communication infrastructure: this is a description of the mobile telecommunication technologies and networks; device type: this relates to the type of device being used such as PDA, sensor, or tablet PC; data display: describes how the data will be displayed to the user and transmitted such as images, e-mail and textual data; application purpose: identification of the objective for the m-health system; application domain: definition of the area that the system will be implemented. Healthcare stakeholders and system implementer can use the reference model presented in this chapter to understand the security implications of the proposed system, identify the technological infrastructure, business requirements and operational needs of the m-health systems being implemented. A reference model to encapsulate the emerging m-health field is needed for cumulative progress in this field. Currently, the m-health field is disjointed and it is often unclear what constitutes an m-health system. In the future, m-health applications will take advantage of technological advances such as device miniaturizations, device convergence, high-speed mobile networks, and improved medical sensors. This will lead to the increased diffusion of clinical m-health systems requiring better understanding of the components, which constitute the m-health system.