Both reduced glutathione (GSH) and and its oxidized form, glutathione disulfide (GSSG), enhance neutrophil locomotion. The enhancement is mainly due to a chemokinetic effect, and partly due to a chemotactic effect. A number of other SH-group containing compounds were not effective in enhancing neutrophil migration. While random locomotion is not inhibited by the slowly-penetrating sulfhydryl agent 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), the enhancement of migration due to GSH is completely inhibited. Pretreatment of neutrophils with pertussis toxin completely inhibited the GSH-induced stimulation of locomotion, suggesting that stimulation of migration by glutathione was mediated by a pertussis toxin sensitive G-protein. Chemotaxis towards GSH is inhibited by the same agents that inhibit fMet-Leu-Phe induced chemotaxis, except that colchicine was a more effective inhibitor of GSH-induced chemotaxis than of fMet-Leu-Phe directed chemotaxis. GSH enhances the intracellular concentration of cGMP, which might indicate that the effect on neutrophil locomotion is mediated by an effect on cGMP.