We reviewed the clinical presentation, subsequent course, and outcome of 98 patients with alpha 1-antitrypsin deficiency seen at our institution during the past 20 years to obtain answers to the following questions: (1) What prognostic factors aid in determining the course of liver disease in affected patients? (2) When is the appropriate time for referral to a liver transplant center? (3) Does breast-feeding prevent chronic liver disease? (4) What is the incidence of severe liver disease in family members? Our analysis revealed that the initial values of alanine aminotransferase, prothrombin time, and trypsin inhibitory capacity may have prognostic value. During clinical follow-up the recurrence or persistence of hyperbilirubinemia along with deteriorating results of coagulation studies indicated the need for liver transplantation because of imminent poor outcome. Girls had a worse prognosis than boys. Initial breast-feeding versus feeding of commercial formulas did not influence overall overcome. The incidence of significant liver disease among "at risk" siblings was 21% (3/14); if one assumes mendelian inheritance from heterozygous parents, the overall risk for siblings in our families was 5%.