The present review was dedicated to laccase-the enzyme, belonging to the group of multinuclear copper, containing so called "blue" oxidases. The molecular structure, metals content, substrate specificity, and other physicochemical properties were described in this article. The authors considered the mechanism of enzymatic action and electrocatalytic oxygen reduction catalyzed by laccase in details. The data of laccase application in organic synthesis, biosensors, and immunoenzyme assay were presented.