We examined the effect or dietary doses of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) on adrenocortical responses to behavioral stress in borderline hypertensive (BH) men using a randomized, double-blind, caffeine-placebo crossover design. Cortisol levels were assessed in BH men and matched normotensive (NT) controls at rest and in response to 35 min of continuous work on a psychomotor task alternating with mental arithmetic. Caffeine at rest elevated cortisol among BHs hut not among NTs. Both groups showed significant cortisol responses to caffeine combined with the tasks. These findings may have implications for the dietary use of caffeine in persons at risk for hypertension when faced with stressful situations.