Viperid snake venoms are rich sources of metalloproteinases, a numerous family of zinc-dependent enzymes which exert multiple deleterious activities. Snake venom metalloproteinases (SVMPs) belong to the superfamily of "metzincin's" and induce local effects, i.e. hemorrhage, myonecrosis, edema, blistering, dermonecrosis and inflammation, in addition to systemic alterations such hemorrhage, coagulations, defibrinogenation and inhibition of platelet aggregation, among others. Moreover, SVMPs contribute to the spreading of the other venom components from the site of injection. In Brazil, the snake of the Bothrops species (Viperidae family) is found in practically all the territory, being responsible for about 90% the accidents. The specie Bothrops moojeni can be found mainly in Minas Gerais, at the regions of the Triangulo Mineiro and Alto Paranaiba. A characteristic of this specie is that its venom presents high proteolytic action. This work describes the purification of a proteolytic enzyme from the Bothrops moojeni (Caiçaca) venom. The venom initially was diluted in buffer ammonium bicarbonate (AMBIC) 0.05M, pH= 7.8 and centrifuged at 10000 x g for 10 min at 4ºC. The supernatant was applied in a column of ionic exchange DEAE-Sephacel equilibrated and eluted with the same buffer, establishing a convex gradient of concentration (0.05-0.40M). In this chromatography the fractions D1, D2, D3, D4 and D4a were collected. The D2 fraction was rechromatograped in Sephadex G-75 column equilibrated and eluted with AMBIC (0.05M, pH = 7.8) obtaining the fractions Sma, Smb and Smc. The Smb fraction presented one band of 23.5 kDa at SDS-polyacrylamide gel electrophoresis in denaturing conditions (-mercaptoethanol). This fraction presented high proteolytic activity to the chains A and B of the fibrinogen bovine and to the casein. The fibrinogenolytic activity was inhibited by EDTA e 1,10-phenantroline, indicating that this low molecular weight proteolytic enzyme belonging to the class of the metalloprotease P-I.