Hypochlorous acid (HOCl) is a bactericidal compound formed by activated neutrophils during inflammation. Overproduction of HOCl causes damage to tissues at the site of neutrophil accumulation. The deleterious effects of excessive HOCl formation can be attenuated using antioxidants. Thiols and thioethers are known to be very effective HOCl scavengers. In the present study, the potency of several sulfurcontaining compounds to protect acetylcholinesterase, glutathione Stransferase P1-1 (GST P1-1) and α1-antiproteinease against inactivation by HOCl was determined. Surprisingly, glutathione disulfide was an effective protector of acetylcholinesterase against hypochlorous acid. Glutathione disulfide did not provide protection for GST P1-1 and α1-antiproteinease against oxidative inactivation by HOCl. The implications of this finding are discussed.