Aim: to assess the levels of lipid peroxidation (LPO) products of malondialdehyde (MDA) and glutathione system in patients with the exacerbation of chronic pancreatitis (CP). Material and Methods: 80 patients with exacerbation of CP and 23 controls have been investigated. The level of reduced glutathione (GSH) and activity of enzymes of glutathione reductase (GR), glutathione transferase (GT), glutathione peroxidase (GP) have been determined in plasma and erythrocytes, while the MDA has been studied in plasma. Results: The MDA levels in plasma were higher in CP patients as against the values of the controls. The MDA level correlated positively with intensity of pain. Increased GSH concentration and activity of GT were revealed in plasma. In the erythrocytes reduction in GP activity and GSH concentration were determined. Conclusion: In the exacerbation of chronic pancreatitis lipid peroxidation and reduced antioxidant protection have been activated.