OBJECTIVE: To determine whether urinary cyclic GMP (cGMP), which mediates the actions of the vasodilators nitric oxide and atrial natriuretic factor, is inversely related to blood pressure (BP) reactivity. In previous work, we found that urinary cGMP was inversely related to diastolic BP, but cGMP levels were higher among individuals presumed to have increased adrenergic activity, increased reactivity, and increased risk of hypertension (blacks, individuals with a family history of hypertension). METHOD: We measured 24-hour urinary cGMP levels in a substudy of 529 individuals in the Coronary Artery Risk Development in Young Adults (CARDIA) study; the sample was 23 to 35 years of age and approximately balanced for race (black/white) and gender. BP reactivity to stressors (video game, star-tracing, cold pressor) was tested 3 years earlier. Baseline BP was included as a covariate in all analyses. RESULTS: Diastolic BP reactivity to cold pressor was inversely related to cGMP excretion (p < .05); the relationship was strongest among black women with a family history of hypertension (partial r = -.33, p < .01). Systolic BP reactivity to star-tracing was also inversely related to cGMP (p < .01); the relationship for both star-tracing and video game stressors was strongest among black men (partial r values = -.25 and -.24, respectively; p values < .01). CONCLUSIONS: The results indicate that vasodilatory activity may impact the BP response to stress through modulation of adrenergic activation, particularly among blacks.