Leukotriene A₄, hydrolase is a zinc-containing enzyme which catalyzes the hydrolysis of LTA₄ to LTB₄ a proinflammatory mediator. The enzyme also exhibits an aminopeptidase activity. Due to its biological importance, it is of considerable interest to develop selective inhibitors of this enzyme. The design and synthesis of a number of potent β-amino hydroxylamine and amino hydroxamic acid inhibitors are described here. It was found that having a free amine was essential far high activity. Hydroxylamines were found to be about an order of magnitude less potent than their analogous hydroxamic acids. Our investigation of amino hydroxamic acids as inhibitors of leukotriene A₄ hydrolase has led to the development of hydroxamates 16 and 17, which are among the most potent inhibitors found to date. These, compounds were found to be competitive inhibitors with K_i, values of 1.6 nM and 3.4 nM respectively, against the peptidase activity. Inhibitor 16 has an IC₅₀ value of ≤ 0.15 μM against the epoxide hydrolase activity and is also potent against the production of LTB₄ by isolated polymorphonuclear leukocytes (PMNL) activated with ionophore A23187 (IC₅₀ ≈ 0.3 μM).