Abstract: Objective To observe the effect of intra-pleural injection of PA-MSHA vaccine on hepatic pleural exudates. Methods After closed drainage of pleural exudates,5ml PA-MSHA was injected into the thoracic cavity.Chest X-ray or ultrasound was performed to show the pleural exudates 3 days after injection of PA-MSHA vaccine.Patients who had a poor response to PA-MSHA were observed one week after a second injection of PA-MSHA vaccine.All patients underwent expectant treatment according to their biochemical test findings. Results Different extents of chest pain and fever occurred in some patients.The total efficacy was 85.7%.The symptoms were improved in 19 of the 28 patients after the first injection of PA-MSHA vaccine. Conclusion Intra-pleural injection of PA-MSHA vaccine is an effective treatment modality for pleural exudates.