Screening of fibrinolytic enzymes from bacteria, yeasts, molds and basidiomycetes was done. All bacteria except Serratia plymuthica IFO 3055 had fibrinolytic activity under aerobic or anaerobic culture conditions. Yeasts cultured under both aerobic and anaerobic conditions dissolved fibrin. All molds cultured under anaerobic conditions dissolved fibrin. On the other hand, fibrinolytic activity of Pleurotus sp. was higher in basidiomycetes.