MeOH extracts of sixteen herbal drugs were tested for the effects on bovine adrenal tyrosine hydroxylase and dopamine ${eta}-hydroxylase$. The MeOH extracts of Paeoniae Radix and Pinelliae Tuber showed 65% inhibition on the tyrosine hydroxylase activity at the concentration of 100 $mu$g in the enzyme reaction mixture. Those of Paeoniae Radix, Pinelliae Tuber and Evodiae Fructus showed 87, 84 and 62%, respectively, on the dopamine ${eta}-hydroxylase$ activity.