Gender and ethnic disparities in cardiovascular disease and mortality have spurred interest in the epidemiology of stress hormone production. Greater disease burden among men and Blacks raises the possibility of gender and ethnic differences in stress hormone production. The purpose of this study was to determine whether urinary stress hormones were higher among men and Blacks in a population-based sample. Urinary hormone analysis permits a time-integrated assessment of the stress response system. However, differences in collection and standardization strategies have led to inconsistent findings. Subjects were an ethnically diverse population-based sample of 229 men and women aged 50 to 67 who provided an overnight urine specimen. Urine concentration was standardized using a traditional creatinine-based approach as well as a new method which accounts for muscle mass. Using creatinine standardization, no gender or ethnic differences were noted in epinephrine or cortisol production. Norepinephrine levels were higher among women compared to men (p = .001), however. After accounting for muscle mass, both epinephrine (p = .018) and norepinephrine (p = .033) levels were higher among men compared to women. No significant differences in cortisol production were found by gender or ethnicity. The consistency of these results with previous studies of 24 hour urine samples suggests muscle mass should be accounted for when comparing overnight urinary hormone values across gender and ethnicity.