1. The aim of the present study was to assess the effect of ganglion blockade on blood pressure in cortisol treated human subjects. 2. Four healthy male subjects were treated with cortisol 80 mg/day for a 5-day period. Ganglion blockade was achieved by intravenous trimethaphan. 3. Ganglion blockade did not significantly alter blood pressure in the pretreatment phase or on the last day of cortisol treatment. 4. Taken together with our previous observations that sympathetic activity is unaltered or reduced by cortisol, these results suggest that cortisol induced hypertension in humans is not a result of overactivity of the autonomic nervous system.