Mitochondrial biology reinvented itself and became a new world that has attracted new scientists influencing every field of biomedical research. Mitochondrial research is growing and changing, as reflected by the exponential rise in the number of conferences covering mitochondrial biology and the role of mitochondria in diseases ranging from neurodegenerative diseases,metabolic diseases and genetic muscular dystrophies toimmunopathologies and cancer. As the awareness of the essential role of mitochondria in pathology rose, a demand for new approaches to measure mitochondrial function resulted in the robust development of new forms of microscopy and spectroscopy that opened windows into previously unknown aspects of mitochondrial biology. Two Conferences provided an outstanding representation of this state of affairs, the Gordon Research Conference Mitochondrial Dynamics and Signaling (Ventura, California March 17-22, 2019) and the FASEB Conference Mitochondrial Biogenesis and Dynamics in Health and Disease (Palm Springs, California May 19-24, 2019). These conferences well reflected the explosion of the field of mitochondrial communication within the cell, between cells and across organs, as well as the budding of a new field on the definition of individual mitochondria and the identification of subtypes with diverse structural features that may serve different specific functions. Through our participation in these meetings, we conceived the idea to cover some of these topics in the Research Topic “Mitochondria in Health and Disease” of Frontiers in Physiology - Mitochondrial Research Specialty Section. Fitting the tradition of Frontiers, our contributors have generated a platform incuding both solid data and new concepts, as radical and courageous as they can be. We are pleased with the outcome and we hope that our readers will share our enthusiasm.