The health effects of occupational exposure to bioaerosols were reviewed. The types of health hazards that bioaerosol contamination of industrial workplaces can present were discussed. Bioaerosols in industrial workplaces may present a risk of microbial infection, allergic reaction or respirator sensitization to microorganisms, allergic reaction or sensitization to nonmicrobial proteinaceous materials, or a risk of a toxicological reaction (toxicosis) to microbial products or cellular components. Microbial infections may result from the presence of infectious materials, opportunistic pathogens, or zoonoses. Although infectious materials are commonly associated with hospital or laboratory environments, workers in other environments such as waste treatment personnel can also come into contact with infectious agents. Toxicoses can result from exposure to endotoxins and mycotoxins. Sources of workplace bioaerosols were discussed. Bioaerosols in the workplace can originate from three sources: as contaminants in materials that workers are handling, contamination originating from nonwork material sources such as in air conditioning systems or humidifiers, and from biologically active materials that form an integral part of the workplace material such as nonmicrobial allergenic bioaerosols created during food processing. Workplaces and work materials where occupational exposure to bioaerosols is known to affect workers' health were described. These included agricultural and food production operations or facilities, factories and industrial settings, and the biotechnology industry. Bioaerosol samplers available for industrial workplaces were described. Practical considerations for performing bioaerosol sampling in workplaces were discussed. These include adopting an appropriate sampling strategy, deciding where to position the samplers and when to sample, and how to best handle collected samples.