Reference intervals for urinary epinephrine, norepinephrine and cortisol in 120 healthy individuals performing their routine work were established according to the International Union of Pure and Applied Chemistry (IUPAC) and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) for use in the risk assessment of exposure to occupational stress. Reference intervals were established for three different times of the day: in morning samples (05.45-07.15) the limit of detection (LOD) was 2.10 micromol epinephrine/mol creatinine (82 women) and 2.86 micromol epinephrine/mol creatinine (37 men), and the reference interval was 3.6-29.1 micromol norepinephrine/mol creatinine and 2.3-52.8 micromol cortisol/mol creatinine (119 women and men); in afternoon samples (15.30-18.30) the reference interval was 0.64-10.8 micromol epinephrine/mol creatinine (82 women), 1.20-11.2 micromol/epinephrine/mol creatinine (36 men), 11.0-54.1 micromol/ norepinephrine/mol creatinine and LOD was 42.4 micromol cortisol/mol creatinine (117 women and men); in evening samples (21.45-23.45) LOD was 8.66 micromol epinephrine/mol creatinine (81 women) and 7.99 micromol/epinephrine/mol creatinine (36 men), the reference interval was 11.0-54.1 micromol norepinephrine/mol creatinine, and LOD was 42.4 micromol cortisol/mol creatinine (117 women and men). A variance component model for describing the effects of age, body mass index (BMI), diurnal variation, gender, days of sick leave during past year and smoking habits was established. Women showed a higher morning value but excreted lower amounts of epinephrine during the day as compared to men. No gender differences could be demonstrated for the excretion of norepinephrine and cortisol. Excretion of epinephrine and norepinephrine increased with smoking and decreased with increased BMI. No effects were observed in the excretion of cortisol.