Cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD). However, only a minority of cigarette smokers develop symptomatic disease. Studies of families and twins suggest that genetic factors also contribute to the development of COPD. We present a detailed literature review of the genes which have been investigated as potential risk factors for this disease. The only established genetic risk factor for COPD is homozygosity for the Z allele of the alpha1-antitrypsin gene. Heterozygotes for the Z allele may also be at increased risk. Other mutations affecting the structure of alpha1-antitrypsin or the regulation of gene expression have been identified as risk factors. Genes, including those for alpha1-antichymotrypsin, alpha2-macroglobulin, vitamin D-binding protein and blood group antigens, have also been associated with the development of COPD. Variants of the cystic fibrosis transmembrane regulator gene have been identified as risk factors for disseminated bronchiectasis. The genetic basis to chronic obstructive pulmonary disease has begun to be elucidated and it is likely that several genes will be implicated in the pathogenesis of this disease. The knowledge gained from such studies may also prove relevant to other inflammatory diseases.