Selenium is an essential trace element for living creatures from all three domains of life (Bacteria, Archaea, Eukaryota), but it is toxic in high concentrations. Selenium oxyanions (selenate and selenite) are water soluble and highly toxic, and get released in the environment through natural processes or through human activity (industry, agriculture). Some bacterias are capable of coping with higher concentrations of toxic selenic forms, i. e. selenium oxyanions in its environment, and that is possible due to different mechanisms possessed by those bacteria like reduction of selenium oxyanions in a process of anaerobic respiration or, not as often, aerobic reduction through processes of detoxification. Bacteria that reduce selenium oxyanions produce nanospheres of elemental selenium that have specific physical properties, or rarely methylate them and reduce them to selenide, producing gaseous methylated selenium compounds. The main objective of this paper is to collect the current knowledge of bacteria that exhibit some kind of resistance to selenium – to its toxic forms, as well as the mechanisms whit which it is obtained. The mechanisms that provide resistance to selenium are not jet well explained, especially the ones that occure in aerobic conditions, and many questions remain unanswered like the ones regarding the expulsion of the selenium nanospheres out of the bacteria cells.