PiZZ-deficient patients affected by a severe panlobular emphysema were treated with an infusion of industrial concentrates of purified &agr;1-antitrypsin (AAT). A treatment protocol was followed and the pharmacokinetic parameters were determined. The aim of this investigation was to consider the tissue distribution of AAT injected into untreated and treated patients, as well as into controls, in order to locate the labelled protein and map the kinetics of the protein deposit.Scintigraphies carried out on PiZZ patients and on controls confirmed a 3-pool pharmacokinetic model of AAT distribution. Three organs accounted for the predominant deposition of AAT: the liver, lungs and a very limited area of the upper digestive tract. At time 0, the distribution of the protein differed between controls and untreated patients. After 6 months of replacement therapy, the tissue distribution of AAT among treated and untreated PiZZ-deficient patients was not similar.The liver is one of the essential organs affected by the infusion of AAT. This study demonstrated that the digestive tissues are also affected by this replacement therapy. These observations should be useful in predicting tissue metabolism of the injected preparation, particularly when alternative routes of AAT administration are now possible.