APART from emphysema of the bullous type, which is not unusual and occurs in all parts of the lung, there appears to be a different, more uncommon form. Its characteristics are striking enough for one to regard it as an entity, for which we propose the name "progressive bilateral bullous emphysema." The disease is usually recognized after the second decade and is apparently limited to men. The process begins in the apexes and gradually increases, until in extreme cases both upper and lower lobes are replaced by large cystlike areas. The usual history is that of cough, slowly increasing dyspnea, recurrent infections of the respiratory tract, asthma-like attacks and cachexia. Death occurs from intercurrent infections or when insufficient pulmonary tissue is left to carry on normal respiratory exchange. The following 8 cases were observed in the Jefferson Hospital during a period of three years. Case 1. —A 48 year old