Big data" in health is no longer a trendy buzzword but a reality. Abundant amount of data is amassed from a variety of sources including electronic health records (EHRs), administrative claims, wearables and mobile devices, genomic sequencing, medical imaging, even social media and the broad Internet, to name a few. Unfortunately, the bridge from being able to process these big data sets to knowledge discovery is still insurmountably challenging. With artificial intelligence being tested and implemented across the health and health care continuum, intelligent systems and their applications in health have the potential to transform the way how we learn from a wide range of data sources to ultimately improve health outcomes. Nevertheless, the increasing complexity of today's biomedical research requires more than traditional, single point-of-view approaches. Indeed, (big-)data-driven approaches that can reveal patterns in massive heterogeneous data sets and make clinically relevant predictions are becoming increasingly common in translational research. This Special Issue, "Intelligent Systems in Health," is an extension of a special track on the same topic in the 30th International Conference on Industrial, Engineering, Other Applications of Applied Intelligent Systems (IEA/AIE) hosted at the Université d'Artois in Arras, France. Five journal extensions have gone through additional peer-review and were accepted to this Special Issue. The five articles are showcases of the state-of-the-art research and development efforts that effectively apply intelligent algorithms and systems on a wide range of heterogeneous data sources. ElTayeby et al. 1 developed and tested machine learning models using different types-text, image, and video-social media data (i.e. Facebook) to detect binge drinking (i.e. excessive alcohol use that brings a person's blood alcohol concentration to 0.08 grams percent or above 2) among