The author briefly summarizes the relationship between oxidative stress and changes in metal ion metabolism in pathological processes. Essential metal ions such as Ca, Mg, Fe, Cu, Zn, Se are essential in the living organisms, their metabolism and intracellular concentration are strictly regulated. Externally or intrinsically, altered metal ion metabolism can lead to metal ion accumulation or metal ion deficiency. Excess amounts of redox-active essential metals such as Fe, Cu, Co, Cr, Ni can induce free radicals under certain circumstances that cause inflammation, cell damage, and cancerous changes, although the molecular mechanism is still unclear in every detail. Changes in the metabolism of non-essential and non-variable valence metal ions also affect redox homeostasis. Despite the fact that each metal can react in a unique way and with different mechanisms, similar processes occur, where both metal deficiency and excessive metal induce oxidative stress. Antioxidant defense system is damaged, free radicals produced alter the redox balance, and redox homeostasis changed induces the production of cytokines and other transcription factors that affect the intracellular signaling pathways and affect the development of various diseases, including metabolic, cardiovascular, neurological diseases and cancer. Orv Hetil. 2019; 160(36): 1407–1416.