Chronically elevated HPA activity has often been associated with fear and anxiety, but there is evidence that single administrations of glucocorticoids may acutely reduce fear. Moreover, peri-traumatic cortisol elevation may protect against development of post-traumatic stress disorder. Hypervigilant processing of threat information plays a role in anxiety disorders and although relations with HPA functioning have been established, causality of these relations remains unclear. Presently, self-reported anxiety and response time patterns on a masked emotional Stroop task with fearful faces were measured in 20 healthy young men after double-blind, placebo-controlled oral administration of 40 mg cortisol. The masked fearful Stroop task measures vocal colornaming response latencies for pictures of neutral and fearful faces presented below the threshold for conscious perception. Results showed increased response times on trials for fearful compared to neutral faces after placebo, but this emotional Stroop effect was acutely abolished by cortisol administration. This effect was most pronounced in subjects with heightened anxiety levels. This is the first evidence showing that exogenous cortisol acutely reduces anxiety-driven selective attention to threat. These results extend earlier findings of acute fear reduction after glucocorticoid administration. This suggests interactions of HPA functioning and vigilant attention in the pathogenesis of anxiety disorders. Possible neuroendocrine mechanisms of action are discussed.