Abstract: Objective: To evaluate video assisted minithoracotomy(VAMT) in the treatment of the subacute pyothorax and the treatment principles.Methods: From August 1999 to July 2002,VAMT was performed in 7 cases of the subacute pyothoraxs.In the course of operation,pus liquid,clot,as well as necrotic tissues were cleared and visceral fiberboard on the lung surface was stripped to make the compressed lung fully expand.As for those with long case history and serious fiberboard adhesion,a "#" cut might be preferred.In this case,the fiberboard on the wall of lung was not stripped in order to prevent blood oozing.Dry gauze could be applied to clean the fiberboard on the thoracic cavity wall so as to remove pus moss.Results: All of the 7 cases recovered well with no severe postoperative complications.Conclusions: VAMT contributes greatly to the eradication of pathogeny,healing of the pus cavity and recovering of lung function.This treatment has proved to be highly effective,and is especially suitable for the patients who are very weak,very young or the patients with a long case history.