Pneumopyopericardium is a rare disease, the etiology of which can be traumatic or non-traumatic. Today the most common cause of non-traumatic disease seems to be ulceration or carcinoma in the lower esophagus or upper stomach. The present cases were caused by ulcerations in two patients and a postoperative penetrating abscess in the third. All had connections with surgery in the region. Chest radiography disclosing fluid and gas in the expanded pericardium was the main diagnostic method. The prognosis is poor and all three patients died.