In the U.S., OSHA has mandated permissible exposure levels (PELs) and NIOSH has developed recommended exposure levels or RELs for many workplace chemicals. These levels reflect the agencies' concerns for adverse health effects in workers who breathe in these chemicals from workplace air. In addition to setting PELs or RELs, OSHA and/or NIOSH sometimes recommend biological monitoring of chemicals or medical examinations of workers to detect adverse health effects after exposure to chemicals. Biological monitoring recommendations could include the measurement of the substance itself or its metabolite or metabolites in various biological media such as blood, urine, expired air, hair, adipose tissue, etc. Medical examinations could include physical examinations or tests of a specific organ system, such as pulmonary function testing or chest radiographs for the lung or specific diagnostic tests that would indicate an adverse effect from a chemical exposure, such as measuring a decrease in plasma cholinesterase. The tests summarized in this poster include OSHA and NIOSH recommendations, as well as recommendations taken from medical reference books and textbooks. This updated poster (the original poster, NIOSH publication No. 98-105, was published in 1998) reflects changes in OSHA's requirements for medical surveillance. This revision also includes updates of the medical tests recommended by NIOSH and the medical references previously cited, as well as information gathered from four additional reference books published in the intervening years.