The metabolic products of peroxide oxidation of cellular membrane lipids and the activity of the antioxidant enzyme superoxidismutase in blood plasma was determined in 68 patients with acute pelvic inflammatory disease and exacerbation of chronic pelvic inflammatory disease. The analyses were done before treatment, after routine antibiotic therapy, and after low energy laser radiation treatment. During acute inflammation and exacerbation of chronic inflammation, peroxide oxidation of cellular membrane lipids intensifies and antioxidant enzyme activity decreases. Helium-neon laser rays in addition to routine antibiotics appear to stabilize peroxide oxidation and normalize antioxidation enzyme activity more than antibiotics alone.