This paper presents an overview of the physiological properties of copper (Cu), an essential trace element playing an important role in the human metabolism, primarily as a cofactor of many metalloenzymes. The maintenance of Cu homeostasis is required for proper functioning of the human body. However, when the disturbance of Cu homeostasis occurs, strong pathological manifestations may develop. Wilsons disease and idiopathic toxicosis are examples of severe chronic liver diseases that are the results of genetic predisposition to the hepatic accumulation of copper. Conversely, congenital Menkes disease is manifested as serious Cus nutritional deficiency. Although Cu is necessary for many life processes, it is also a powerful weapon used since the ancient times against many microorganisms. Finally, the theories of Cu antimicrobial and antiviral mechanisms of action are summarized, including contemporary and potential future utilizations in medical and non-medical fields of human life. Key words: copper metalloenzymes copper toxicity copper deficiency copper-related diseases copper applications.