This studies were measure the cortisol from salivary and serum of fire-fighters, who are relatively always exposed to highly dangerous and unsafe working conditions in which they should bring a fire under control or rescue people in danger situations et cetera, therefore both physically and mentally stressed-out, and comparatively analyzed the correlation between the two cortisol levels. The salivary and serum samples of 133 active fire fighters. These were collected at 8:30am, when leaving for work. The salivary cortisol analysis was carried out with enzyme immunoassay, and the serum cortisol analysis utilized chemiluminescence immunoassay. On the morning of testing, the salivary cortisol concentration was 1.92±0.73(0.51~5.85)㎍/㎗, while the cortisol concentration of serum was 14.93±4.23(4.45~25.85)㎍/㎗. Results were grouped according to ages, smoking, drinking habit, and duty type. Higher smoking and drinking produced a statistically significant increase in salivary and serum cortisol concentration. Cortisol concentrations according to type or duty followed by emergency rescue, fire suppression, rescue, miscellaneous. There is a statistically significant correlation between salivary and serum cortisol concentrations. The results show that a significant correlation between salivary and serum cortisol concentrations exists in fire fighters. It is judged that noninvasive methods salivary cortisol could be used in place of serum cortisol to measure cortisol levels when considering factors such as convenience of sample collection and cost. Keywords : cortisol, saliva, serum, correlation, fire fighter