Our proposal is highly responsive to the NORA RFA and NIOSH's agenda. It provides a unique opportunity to study periodic medical examinations, a traditional occupational health intervention, in firefighters, a high priority group for NIOSH. From 1990 to 1992, over 250 firefighters lost their lives and approximately 100,000 were injured in the line of duty. Because this work is hazardous and strenuous, regular medical examinations are recommended for all firefighters. It is unknown, however, if examinations can prevent morbidity and mortality, and little evidence is available to support current fitness for duty standards. We propose to prospectively study outcomes based on fitness and health ratings. We will continue the prospective study of about 340 firefighters with an expected 1,700 person-years of follow-up. Since 1996, periodic questionnaire, physical and laboratory examination data have been obtained and will be repeated on a yearly basis during the study period. For each examination, each firefighter is classified on various parameters including passing/failing National Fire Protection Association (NFPA) medical requirements and other proposed fitness criteria, overall health/morbidity ratings, and degree of hearing loss. Specific aims include: 1) evaluation of the ability of NFPA, other objective fitness guidelines, and baseline overall health ratings to predict increased risks of injury, cardiac events or other adverse outcomes; 2) to determine whether firefighters with abnormal hearing are at an increased risk of injury or other adverse outcomes; 3) further evaluate the clinical utility of various components of the baseline and periodic medical examinations; and 4) to integrate the information derived from the studies above to contribute to the development of evidence-based guidelines for the medical evaluation of firefighters. The proposed research is very responsive to the NORA RFA because periodic examinations are a core Occupational Health Services program. The results will be generalizable because there are one million plus American firefighters. Given the large number of firefighters and their high rate of injury and death, firefighters are a most appropriate target for such intervention. In summary, our proposal seeks to improve the medical examination process for this important group based on prospective epidemiologic evidence.