The proteolytic activity regarding different substrates in the organs of the Black Sea mollusks was studied: <i>Rapana venosa</i>, Valenciennes, 1846, <i>Mytilus galloprovincialis</i>, Lamarck, 1819 and <i>Donax trunculus</i>, Linnaeus, 1758. Significant collagenolytic activity and lesser fibrinolytic activity were found in the salivary glands of <i>Rapana </i>and hepatopancreas of mussels. The organ specificity of the proteolytic enzymes' sets was revealed. Molecular masses of gelatinases were determined by electrophoresis. Gelatinase zymograms showed a variety of proteinases, among which matrix metalloproteinases were quite diverse. The results enable to recommend <i>Rapana</i> and mussel as a promising source of preparations with collagen and fibrinolytic activity, which are important in view of medical use.