Summary—The effects of clonidine on adrenal medulla catecholamines levels were studied in normotensive rats. Intraperitoneal injections (50, 100 μ/kg) of clonidine caused a dose‐dependent decrease in adrenaline content of the gland. This effect was suppressed by denervation of the adrenal medulla,i.e.unilateral section of splanchnic fibers performed 5 days before. These results demonstrate that clonidine decreases the catecholamine content of the adrenal medulla only through a central action. They suggest that the adrenal medulla is involved in the hypotensive effect of cloni