Archaea, along with bacteria and eucarya are the three domains of life. These microorganisms inhabit variable natural environments but they are also important part of human physiological flora. In this paper we describe archaeal morphology and physiology. We also review the state of knowledge about archaea associated with human microbiome. The potential role of these microorganisms in etiopathogenesis of some human diseases is discussed, as well. Finally, we consider archaeal susceptibility/resistance to antimicrobial agents, including antibiotics.