Health information systems (HIS) are crucial for guiding sound public health policies and programs. Information systems are complex entities formed of diverse parts with one common plan and purpose. A critical feature of information systems is that their components have regular interactions and interdependences. The systems should be flexible and adaptable to changes in burden and circumstances. Building health information systems should start by complementing what is currently in place and improving existing systems. It should use new technologies and include training for collectors and users. Most importantly, the data and findings should be rigorously analysed, interpreted, translated, disseminated and used to inform implementation. In this chapter, we provide a brief review of HIS and an example using the Global Burden of Disease as a case study of how different sources of HIS are used to estimate the burden of a disease to guide policies and programs.