Data from a community-based random sample of 3,606 adults 40 to 69 years of age residing in Beijing, China, were used to examine the relationship between occupational exposures to dusts and gases/fumes and physician-diagnosed asthma. The prevalence of asthma was 3.9 percent for men and 3.8 percent for women. After adjusting for sex, age, education, residential areas, indoor coal combustion, and smoking status, the attributable risks of asthma were 1.7 percent and 1.2 percent for dust and gas/fume exposure, respectively. The adjusted odds ratios of asthma for dust and gas/fume exposed groups were 1.6 (95 percent confidence interval [CI], 1.1 to 2.2) and 1.4 (95 percent CI, 0.9 to 2.1), which were independent of sex and smoking status. When subjects were classified into none, dust-only, gas/fume-only, and both-exposure groups, the estimated odds ratios of asthma were 1.3 (95 percent CI, 0.9 to 2.1) in dust-only group, 0.9 (95 percent CI, 0.5 to 1.9) in fume-only group, and 2.1 (95 percent CI, 1.2 to 3.6) in both-exposure group, suggesting a combining effect of the two agents. There was an exposure-response relationship between dust and gas/fume exposures and asthma. In analysis of specific occupational agents, our findings are consistent with previously reported airway effects of organic dusts, but they also suggest that exposure to organic solvents may result in asthma, particularly when combined with dust.