Data from 206 pairs of nuclear family members were analyzed to study the influence of genetic factors on the occurrence of chronic obstructive pulmonary disease (COPD) and its familial aggregation. Results showed that occurrence of COPD appeared in family aggregation. Risk of occurrence of COPD in the relatives (father, mother, brothers and sisters) of the proband with COPD increased by 2.07 times, as compared with relatives of the controls. Significant differences of the risk of COPD in fathers, brothers and sisters between proband and controls were observed, but not in mothers. It suggests relatives of the proband are more susceptible to COPD than those of the controls, and genetic factor may contribute to pathogenesis of COPD.