Glutathione S-transferases (GST) are a family of detoxification isoenzymes that catalyze the conjugation of xenobiotics and their metabolites with reduced glutathione. Lead exposure in rats is known to induce GST isoenzymes in the liver and kidney. These changes in expression have potential use as biomarkers of lead exposure. Because two-dimensional electrophoresis (2-DE) enables one to analyze both protein abundance changes and chemical changes in protein structure, 2-DE was used to determine the effect of in vivo lead exposure on GST isoform expression in rat kidney cytosols. Male Sprague-Dawley rats were exposed to inorganic lead, and proteins were separated by conventional ISO-DALT and NEPHGE-DALT techniques and blotted for immunological identification. Lead exposure caused detectable inductions in both GSTP1 and GSTM1 and quantifiable charge modification in GSTP1. These preliminary data confirm the utility of 2-D electrophoretic GST analysis as indicative of lead exposure and toxicity and support its use for further elaboration of lead's effects on renal protein expression.