N-Acetyl lysyltyrosylcysteine amide is a potent, reversible, specific, and non-toxic tripeptide inhibitor of myeloperoxidase (MPO). N-Acetyl lysyltyrosylcysteine amide effectively inhibits MPO generation of toxic oxidants in vivo. N-Acetyl lysyltyrosylcysteine amide reduces neuronal damage and preserves brain tissue and neurological function in the stroked brain. N-Acetyl lysyltyrosylcysteine amide inhibits MPO-dependent hypochlorous acid (HOCl) generation, protein nitration, and LDL oxidation.