The etiology of chronic obstructive pulmonary disease (COPD) has not been fully understood. This analysis assessed the prevalence of COPD and its risk factors among Canadian men and women. The analysis was based on the data from 7210 subjects aged 35 to 64 years who participated in the first cycle of National Population Health Survey in 1994-1995. COPD was considered present if an affirmative response was given to the question: "Do you have chronic bronchitis or emphysema diagnosed by a health professional?" In order to take the complex survey design into account, analytic weights incorporating a design effect were used in all statistical analyses. The prevalence of COPD was 2.1% in nonsmokers, 2.7% in ex-smokers, and 8.2% in smokers in women. In men, the corresponding prevalence was 0.8%, 2.9%, and 3.5%, respectively. The adjusted odds ratio for current smoking men and women who started smoking before age of 18 years was 3.0 and 5.9 compared with their nonsmoking counterparts. Overweight women demonstrated a 2.4-fold increase in the prevalence of COPD compared with women with normal weight. Men from low-income families had an odds ratio of 3.7 compared with those from high-income families. A history of allergy was significantly related to COPD in both men and women. COPD was common among Canadian women. Early initiation of smoking and being overweight had stronger relationships to the prevalence of COPD in women than in men. On the contrary, household income was more strongly related to COPD for men than for women.