AIM To establish the model of exudative pleurisy induced by alternatively activating complement and to study protection of anti inflammatory drugs on it. METHODS Purified cobra venom factor (CVF) was injected into the pleura, and then exudate volumn, total leukocyte count, protein content and histamine concentration were determined. RESULTS CVF, injected into rat pleura at dose of 0 08～2 mg?kg -1 , induced exudative inflammation in dose dependent and time dependent manner. Both diphehydramine and isoprenaline reduced significantly exudate volume, total leukocyte count, protein content and histamine concentration, while indomethacin, dexamethasone and cyclophosphamide also reduced exudate volume, total leukocyte count and protein content, although they did change the release of histamine. DLF, one of the toxic components in cobra venom, potentiated CVF induced inflammation. CONCLUSION CVF can induce significantly exudative pleurisy sensitive to anti inflammatory agents. DLF has augmentation on CVF induced inflammation.