The perilla [Perilla frutescens (L.)], which belongs to the family Lamiaceae, have been used as a not only important traditional source of oil but also used traditional herbal medicine for treating various disease including depression, anxiety, tumor, cough, bacterial and fungal infections, allergy, detoxication and some intestinal disorders in east asian countries. In this context, luteolin isolated from the P. frutescens inhibited the linoleic acid peroxidation catalyzed by soybean lipoxygenase-1 (EC 1.13.11.12, Type 1) with an IC50 of 5.0 μM. To investigate the inhibitory effect of luteolin on dioxygenase enzyme, we assayed soybean lipoxygenase-1 activity with the inhibitor. Soybean lipoxygenase-1 showed time-dependent inhibition in the presence of luteolin. Increasing luteolin concentrations led to the decrease in both the initial velocity (vi) and the steady-state rate (vs) in the progress curve. Thus luteolin showed a simple reversible noncompetitive slow-binding inhibition against soybean lipoxygenase-1 with kinetic parameter (k3 = 0.056 μM-1min-1, k4,= 0.006 μM-1min-1, Ki app = 0.106 μM).