Background. The frequency of chronic pancreatitis (CP) comorbidity with chronic obstructive pulmonary disease (COPD) has significantly increased recently. It may be accompanied by changes in oxidant-antioxidant homeostasis and activates a cascade of reactions of mutual burdening of these pathologies. The purpose of the current research was to evaluate the intensity of lipid peroxidation, oxidative modification of proteins and the state of individual factors of the antioxidant defense system in the development and course of CP, depending on the comorbid COPD. Materials and methods. Three hundred and seventeen patients were examined, including 62 patients with CP alone (group 1), 132 CP patients with comorbid COPD (group 2), 123 patients with COPD alone (group 3). The content in blood of isolated double bonds in compounds, conjugated dienes, ketodienes and conjugated trienes, malonic aldehyde, nitrites/nitrates, reduced glutathione, the activity of catalase, glutathione-S-transferase, glutathione peroxidase were evaluated in all patients. Results. In CP patients with comorbid COPD, the maximum oxidative stress intensity among the compared groups was registered. There was a reliable increase in the content of malonic aldehyde — by 2.0 times (p < 0.05), isolated double bonds — by 2.2 times (p < 0.05), conjugated dienes — by 1.9 times (p < 0.05), ketodienes and conjugated trienes — by 1.9 times (p < 0.05), nitrites/nitrates — by 2.6 times (p < 0.05). A reliable decrease in reduced glutathione content of erythrocytes was detected: in group 1 — by 1.5 times, in group 2 — by 1.9 times (p < 0.05), in group 3 — by 1.2 times (p < 0.05). The compensatory increase in the activity of glutathione-S-transferase, glutathione peroxidase and blood catalase was revealed: in group 1 — by 1.3, 1.2 and 1.5 times (p < 0.05); in group 2 — by 1.5, 1.3 and 1.8 times (p < 0.05), in group 3 — by 1.2, 1.2 and 1.4 times, respectively (p < 0.05). Conclusions. The comorbid course of CP and COPD is accompanied by the maximum intensity of oxidative and nitrosative stress compared to the isolated course of the disease. An increase was detected in intermediate and final metabolites of peroxide oxidation in the blood, oxidative modification of proteins, nitrites/nitrates in the blood against the background of a deep imbalance of antioxidant defense factors, an increase in ceruloplasmin content in the blood, which requires the administration of antioxidant agents to correct detected disorders and prevent the progression of both comorbid diseases.