Extracellular phospholipase $A_2$ was purified about 65,000-fold from human pleural fluid of patients with tuberculosis by sequential use of column chromatographies on heparin-Sepharose, butyl-Toyopearl and protein-PAK 125 HPLC. The final preparation showed a single band SDS-polyacrylamide gel, and its molecular mass was estimated to be approximately 14,500 daltons. The purified enzyme has a pH optimum of 9.0 and required $Ca^{2+}$ for maximum activity. It hydrolyzed phosphatidylethanolamine more effectively than phosphatidylserine. This enzyme was inhibited by monoclonal antiboty (HP-1) raised against phospholipase $A_2$ enzyme was inhibited by monoclonal antiboty (HP-1) raised against phospholipase $A_2$ from human synovial fluid. These observations suggested the extracellular phospholipase $A_2$ detected in human pleural fluid belongs to the "Group II" family of phopholipase $A_2$.