S-(1,2-Dichlorovinyl)glutathione and S-(1,2-dichlorovinyl)-DL-cysteine are potent nephrotoxins. Agents that inhibit gamma-glutamyl transpeptidase, cysteine conjugate beta-lyase, and renal organic anion transport systems, namely L-(alpha S,5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (AT-125), aminooxyacetic acid, and probenecid, respectively, protected against S-conjugate-induced nephrotoxicity. Furthermore, S-(1,2-dichlorovinyl)-DL-alpha-methylcysteine, which cannot be cleaved by cysteine conjugate beta-lyase, was not nephrotoxic. These results strongly support a role for renal gamma-glutamyl transpeptidase, cysteine conjugate beta-lyase, and organic anion transport systems in S-(1,2-dichlorovinyl)glutathione- and S-(1,2-dichlorovinyl)cysteine-induced nephrotoxicity.