To investigate the role of zinc and copper in the development of pseudoexfoliation (PSX) syndrome, 34 cataract patients with PSX svndrome and 27 cataract patients without PSX syndrome were included in the study and groups were matched for age and gender. During the cataract surgery, lenses were obtained intraoperatively, frozen under liquid nitrogen, and kept at -70 degrees C until processing. Zinc and copper concentrations were measured by atomic absorption spectrophotomeric method after the homogenization (acid hydrolysis) of dried lenses. The mean concentration of zinc in the lens from patients with PSX (20.33 +/- 48.76 mu g/g tissue; range 11.04-42.94 mu g/g tissue) was significantly lower than that measured in the lens of patients without PSX (28.88 +/- 15.32 mu g/g tissue; range 12.02-64.32 tLg/g tissue) (P < 0.05). The mean concentration of copper in the lens from patients with PSX (29.51 +/- 10.05 lig/g tissue; range 12.69-59.71 itg/g tissue) and in the lens of patients without PSX (39.72 +/- 25.64 mu g/g tissue; range 12.38-92.14 mu g/g tissue) Nvas not statistically different. The decreased content of zinc could increase oxidative stress. The results support the role of oxidative stress in the development of PSX in cataract patients.