The aim of this work was to examine the effect of fluoride ions on antioxidative enzyme activity in the pancreas of rats exposed during 4 months to NaF in drinking water. The study was carried out in 30 four-week-old male Wistar FL rats, that were randomly assigned to three equal groups and given distilled water ad libitum for three weeks. Subsequently, two examined groups of animals were exposed to NaF in drinking water: group 1 (10 rats) at 50 mg F(-)/L (2.63 mmol/L), group 2 (10 rats) at 100 mg F(-)/L (5.26 mmol/L). The control group (10 rats) received distilled water. After 4 months the animals were anesthetized with ether prior to collection of pancreas and cardiac blood. Serum concentrations of glucose and fluoride, as well as activities of the cytoplasmic (CuZn-SOD) and the mitochondrial (Mn-SOD) superoxide dismutase, glutathione peroxidase (GSH-Px) and concentrations of malondialdehyde (MDA) in the homogenized pancreas were measured. The activity of CuZn-SOD was reduced by 50% and a tendency to lower activities of Mn-SOD was observed. No changes were noted in the activity of GSH-Px or concentrations of MDA. We conclude that: 1) the fluoride caused hyperglycemia in rats in this study is not accompanied by an activation of the free radical production in the pancreas; 2) the hyperglycemia in the exposed rats cannot be attributed to pancreatic damage caused by fluoride ions (the cause in this case appears to be extrapancreatic); 3) the inhibition of pancreatic CuZn-SOD is probably due to the direct action of fluoride on the enzyme.