Abstract: Leukotrienes (LTs) are a group of metabolites of arachidonic acid through the 5-lipoxygenase pathway. Among these metabolites, LTB₄ is an important mediator of inflammatory disease. Recently, it has been shown that seleno-organic compounds are very biologically active. One of them, Ebselen 2-phenyl-1,2-benzoisoselenazol-3(2H) one is a new seleno-organic compound with very low toxicity while exhibits anti-inflammatory activity. Attempt to search for seleno-organic compounds as anti-inflammatory drugs and establish structure-activity relationships, ten ebselen deriva- tives with modifications in the 2-phenyl moiety were studied with respect to their effects on LTB₄ biosynthesis, p-substituted compounds were shown to have stronger inhibitory activity on LTB₄ biosynthesis than o-substituted compounds and ebselen itself. Among the p-substituted compounds, polar-inducing group-substituted compounds showed stronger activity than compounds substituted with polar-conjugated groups. Among the compounds substituted with polar-inducing groups, strongpolar groups exhibited stronger activity than weakpolar groups.