A group of 187 patients with chronic bronchitis and emphysema were periodically followed up for an average of more than four years to determine if objective benefit was obtained from long-term intermittent positive-pressure breathing (IPPB) home treatment. The 78 patients who used their own IPPB valves at home showed no demonstrable benefit when compared to 109 controls in regard to changes in pulmonary function test values, blood gas values, weight, or number of deaths. Fifty patients treated with IPPB were paired with 50 controls according to results of initial tests of forced expiratory volume in one second (FEV1). Deterioration in FEV1value was 99 ml/yr in the treated group and 44 ml/yr in the controls. Significantly less patients in the treated group showed improvement in FEV1. Long-term IPPB home treatment of emphysematous patients cannot be recommended with assurance of deriving objective improvement.