The corrleations of ventilometry and alpha-1-antitrypsin deficiency were studied in a lot of 105 patients with chronic obstructive bronchopneumopathy associated with various forms of chronic pulmonary suppuration. Alpha-1-antitripsin deficiency was determined by Erikson's gelatin film test, simplified by Keith et al. Ventilation dysfunctions were found in 79% of the cases, predominantly obstructive, mixed, advanced or severe. Alpha-1-antitrypsin deficiency was detected in 11.4% of the patients as against 4.1% in the controls, the deficiency being more accentuated in the mixed (75%) and obstructive (25%) ventilation dysfunctions. Determination of alpha-1-antitrypsin deficiency, corroborated with other investigations may supply useful information for detecting a predisposition and for the evolutive prognosis of these respiratory diseases.