Convergence of life sciences, engineering, and basic sciences has opened new horizons for biologically inspired innovations, and a considerable number of organ-on-a-chip platforms have been developed for mimicking physiological systems of biological organs such as the brain, heart, lung, kidney, liver, and gut. Various biophysicochemical factors can also be introduced into such organ-on-a-chip platforms to study metabolic and systemic effects spanning from drug toxicity to different pathologic manifestations. There is also a pressing need to develop better disease models for common pathologies using variations of these platforms. This can be achieved by recapitulating the unique microenvironment of a disease to investigate the cause and development of abnormal conditions as well as the structural and functional changes resulting from such a pathology. In this review, the organ-on-a-chip platforms that have been developed to model different pathologies of neurodegenerative, cardiovascular, respiratory, hepatic, and digestive systems, along with cancer are summarized. Although the field is still in its infancy, it is anticipated that developing disease model-on-a-chip platforms will likely be a valuable addition to the field of disease modeling, pathology studies, and improved drug discovery.