Medical personnel can play important roles in identifying bioaerosol-related illnesses and responding to them. Medical expertise should be sought after for (a) diagnosis and management of an individual worker with a possible building-related illness (BRI), typically building-related hypersensitivity disease, inhalation fever, or infection, and (b) investigations of populations of workers with building-related symptoms (BRSs). Medical personnel usually participate as members of a team that may include an IH, EHP, IEQ consultant, engineer, epidemiologist, or toxicologist. In the first circumstance, diagnostic confirmation of a BRI is a sentinel health event that raises concern for others with shared building exposures. Such events that involve serious morbidity, mortality, or risk to the community may require notification of public health authorities. In the second circumstance, investigation of symptomatic building occupants may require medical surveillance and /or diagnostic evaluation. This chapter outlines the medical evaluation of possible bioaerosol-related conditions and provides guidelines for physicians and other health-care professionals on (a) identifying and managing BRIs and BRSs due to bioaerosol exposure, and (b) the appropriate roles of health-care professionals in investigation such complaints.