The survey is devoted to the description of properties of proteolytic enzymes of some sea organisms. Structure peculiarities and properties of proteinases of trypsin and chymotrypsin type, carboxypeptidases A and B, aminopeptidase and leucine aminopeptidase of molluscs, stars, shrimps, fishes and other sea organisms have been considered. Data are presented about trypsins typical of the sea organisms which are characterized by high content of asparaginic and glutaminic acids and small values of activation energy of the reactions which they catalyse. Data are discussed concerning stability of enzymes as to heat denaturation, effect of the environment with external values of pH. Based on the similarity of the substrate specificity of enzymes, their sensitivity to inhibitors, it is concluded that the enzymes of the sea organisms and mammals are similar.