Recent advances in free-radical biology and natural product chemistry enhanced our understanding for the molecular pathophysiology of a number of human diseases and application of natural products as novel therapeutic means of intervention. Free radicals are interesting chemical entities with an unpaired electron that makes them highly reactive. They are known to play paradoxical roles in determining human health, sometimes being beneficial e.g., phagocytosis of bacteria, redox signaling and sometimes being toxic e.g., interacting with vital molecules such as DNA to form stable adducts thereby inducing mutagenicity. By virtue of nature, human health system is provided with certain ‘‘electron sinks’’ popularly known as antioxidants that can quench chain propagation induced by free radicals. Perturbation in the delicate balance between prooxidants and antioxidants might increase the susceptibility to several human disorders including inflammation, autoimmune diseases, cancer, diabetes, ischemia–reperfusion (IR) injury, lung injury, neurodegenerative diseases, and cardiovascular diseases. Recent development in the technologies for rapid detection of free radicals, tools to understand the molecular pathophysiology of multi-factorial disorders, ability to isolate and purify the ingredients of natural products, and availability of a multitude of cell lines to study different biological processes have contributed remarkably for efficient and effective utilization of natural products and nutraceuticals for treatment of many disorders. Scientific community in India has contributed remarkably in the areas of oxidative stress and biomedicine. Indian Academy of Biomedical Sciences (IABS) and Society for Free Radical Research-India (SFRR-India) are pioneering bodies providing an academic platform for interaction between scientists and clinicians, thus disseminating the technological and scientific advancements to younger generation. Over the years, conferences held under the banner of IABS and SFRR-India covered a wide variety of topics including genomics and proteomics, free radicalmediated pathogenesis of disease, natural products, antioxidants, radioprotectors, etc., thus presenting new insights into biomedical research. In this series, we have compiled a focused issue of Cell Biochemistry and Biophysics (CBB) that covers an important topic of oxidative stress, which will help in the better understanding of cellular and molecular mechanisms underlying multi-factorial human disorders like cancer, cardiovascular diseases, inflammation, lung diseases, etc. This special issue encapsulates technological and scientific developments in the area of free-radical research, biological concepts of oxidative stress and its connotation in the pathogenesis of various disease processes. This focused issue on ‘‘Oxidative stress in health and disease’’ of CBB contains 24 peer-reviewed research contributions, including five reviews and 19 original articles of which four are related to technological advancements and six are dedicated to therapeutic advances, whereas nine papers contribute to molecular and cellular mechanisms underlying various diseases. Two excellent reviews dealing with angiogenesis and tissue remodeling provide valuable updates in the field of cardiac repair and chronic respiratory diseases. Alagappan et al. state that vascular changes directly add to the airway H. S. Sharma (&) VUmc, University Medical Center, Amsterdam, The Netherlands e-mail: drhssharma@gmail.com