Background: Our aim was to assess psychomental stress and strain among dispatchers in fire departments, particularly during emergency instructions by phone and to evaluate their work ability. Methods: 27 dispatchers and 20 controls were examined. In a protocol, participants recorded 1. phone instructions causing mental stress (event) 2. working time without phone instructions (non-event) 3. breaks. Continuous heart rate (variability), urine catecholamine, salivary cortisol and lymphocytes were measured. To assess the job-related burden, the Work Ability Index (WAI) was applied. Results: Dispatchers demonstrated significantly higher heart rates and reduced standard deviation of all NN (heartbeat-to-heartbeat) intervals (SDNN) than the controls in all phases. WAI of dispatchers was significantly lower than that of the controls. Within the dispatchers, there was a significantly higher rate of inability to work during the past year. Conclusions: The increased heart rate and reduced SDNN of examined dispatchers indicate chronic stress effects as a possible preliminary stage of a health disorder. In respect of the reduced work ability among dispatchers preventive measures are required to reduce the stress situation during their job-performance