Two sisters with alpha 1-antitrypsin deficiency and bronchiectasis are reported. The 53-year-old older sister (propositus) had pneumonia 3 times during her forties. She developed dyspnea on exertion in February, 1988, and a few months later she was seen at our hospital. Her serum alpha 1-antitrypsin level was 11 mg/dl. Vascular markings on chest X-ray were mildly decreased. Bronchography showed generalized cystic bronchiectasis. The younger sister was seen at our hospital at the age of 50. She had been in good health until one year previously when she had developed pneumonia, and thereafter she had suffered from productive cough and dyspnea on exertion. Her alpha 1-antitrypsin level was 22 mg/dl. Chest X-ray showed ring-like shadows and tram lines. Chest CT scans of both sisters revealed cystic changes, dilatation of bronchi, and the connection of these lesions diffusely. The alpha 1-antitrypsin phenotype of these sisters was found to be PiSiiyama (homozygote). Family study revealed that alpha 1-antitrypsin levels of 7 members were intermediate and no members had symptoms. We consider that bronchiectasis may have been related to alpha 1-antitrypsin deficiency in these sisters.