Growing evidence suggests that COPD is causally associated with certain occupational exposures. Few studies have investigated the association using complete job histories and multiple types of occupational exposure. We conducted a case-control study among members of Kaiser Permanente Northwest to evaluate the associations between occupational exposure and COPD. We identified 388 COPD cases aged 45 and over; 356 controls without COPD were frequency matched to cases on age group, sex, and history of smoking. Detailed work and smoking histories were obtained by telephone interview. Certified Industrial Hygienists independently rated each job according to its likelihood of exposure to 8 agents thought to cause COPD. Odds ratios for the association of each exposure (ever-never) with COPD were computed using logistic regression, stratifying on smoking status and adjusting for age, sex, and, for smokers, pack years. Among ever-smokers, occupational exposures most strongly associated with COPD were diesel exhaust (OR=1.7, 95% CI 1.1-2.7) and irritant gases and vapors (OR=1.7, 95% CI 1.2-2.4). Associations with metal dust (OR=1.5, 95% CI 0.95-2.5) and mineral dust (OR=1.5, 95% CI 0.95-2.3) were suggested. In the small group of never-smokers (42 cases and 58 controls), a similar pattern was evident though statistical power was low; the strongest associations found were with diesel exhaust (OR=6.4, 95% CI 1.3-31.6) and mineral dust (OR=3.5, 95% CI 0.94-13.3). In this study, COPD was associated with exposure to diesel exhaust and irritant gases and vapors.