This study aimed to demonstrate the possibility of using data on full employment history to describe occupational patterns of Danish firefighters that may indicate additional hazards encountered by these workers.An established cohort of Danish full-time and part-time/volunteer firefighters was used in the study (N = 9952) as well as occupational history covering the period 1964-2015, which was retrieved from a nationwide pension fund with compulsory membership. The most frequently held employments other than firefighting, together with temporal patterns of these employments, were explored in descriptive analyses.Besides working in the firefighter service, both full-time and part-time/volunteer firefighters had frequently been employed in the military and the police (55% and 38%) and more than 10% of both types of firefighters in a number of blue-collar jobs, including construction-related jobs (eg, masonry, joining, carpentry, insulation, and installation), laundry and dry cleaning, the auto industry, and rubber and plastic production. Part-time/volunteer firefighters had more frequently been employed in the machine industry, fabricated metal production, the wood and furniture industry, and farming. Both types of firefighters were initially employed in other jobs before their employment in firefighting.The cohort of Danish firefighters had frequently been working in other professions potentially exposing them to additional hazardous exposures, and occupational patterns varied by type of firefighter employment. Accounting for full employment history is, for that reason, considered essential when exploring associations between specific professions and health outcomes.