A sensitive, electrochemical method was employed for the simultaneous measurement of reduced and oxidized glutathione in lens cortex, nucleus and capsule epithelia of rabbit lenses, normal human lenses and human cataracts. In addition, aqueous humor from cataract patients was also analyzed. The level of GSSG in the nucleus of human cataracts was significantly higher than that in the nucleus of normal eye bank lenses. The capsule epithelium of intracapsular extracted cataracts possessed high levels of reduced glutathione, despite the fact that much of the glutathione in the cortex and nucleus of the lenses was depleted. Levels of GSH in the aqueous humor of cataract patients were several times higher than those reported for normal aqueous humor. Electrochemical detection proved to be a useful technique for analysis of reduced and oxidized glutathione in lens and aqueous humor, especially when sample size is small, such as for capsule epithelium.