In parallel with the discovery of nev alleies inceasing the complexity of the Pi system, technical refinements have made the classification of an individual with respect to his Pi system relativeiy simple. Isoelectrofocusing in polyacrylamide gels is advantageous method in analyzing pisystem because of ease of performance, high resolution and reproclucibility. Most individuals have the PiMM phenotype resulting in normal plasma a1-antitrypsin (a,-AT) levels. The classical a1-AT deficiency is designated as Pizz in its homogygous form and has 15% of normal plasma a1-AT level, which is known to be associated with increased risk of cirrhosis and primary liver cancer But there is stilJ debate as the cause of this associated liver disease. This study is aimed to know the distribution and contribution of structural variants of a1-AT in South Korean patients with chronic liver diseases inr.uding hepatocellular carcinoma. One hundred thirty nine patients with chronic liver diseases or hepatocellular carcinoma were studied. Rlood sarnples were taken frorn each. Phenotypes of a1-AT were determined by electrofocusing in polyacrylamide gel electrophoresis. The results obtained were as folloas, None of the cases showed deficiency or null variant of a1-AT in patients with chronic liver diseases, hut two cases with hepatocellular carcinoma showed MS phenotype. About half of the cases with chronic liver disease and hepatocellular carcinoma showed homologcius polymorphism of a1-AT phenotype suballeles such as M1M1. M2M2 and M3M3. The distribution of the structural variants of a1-AT phenotype in patients with chronic liver diseases and hepatocellular carcinoma were in order as tollows; M1M1 (51.8%), M1M2(24.5%), M2M2 (7.9%), M3M3 (6.5%), M1M3, (5.8%),M3M3 (2.2%) and M1S (1.3%). In con, lusion, none of the cases with chronic liver diseases showed deficiency or null typed structural variants of a1-AT, but there were two cases with MS phenotype among the 39 patients with hepatocellular carrcinoma. Therefore, genetically determined a1-AT. deficiency seems to be not etiological]y important in South Korean patients with chronic liver disease.