A fibrinolytic enzyme was found in a Gram-negative bacterium, Aeromonas sp. JH1. SDS-PAGE and fibrinzymography showed that it was a 36 kDa, monomeric protein. Of note, the enzyme was highly specific for fibrinogen molecules and the hydrolysis rate of fibrinogen subunits was highest for α, β, and γ chains in that order. The first 15 amino acids of N-terminal sequence were X-D-A-T-G-P-G-G-N-V-X-T-G-K-Y, which was distinguishable from other fibrinolytic enzymes. The optimum pH and temperature of the enzyme were approximately 8.0 and 40°C, respectively. Therefore, these results provide a fibrinolytic enzyme with potent thrombolytic activity from the Aeromonas genus.