Temporary internal jugular vein ligation was employed to mimic surgical procedures carried, out in operations involving the basis of cranium or neck, and clinical pictures like thrombosis of venous sinuses. Our purpose was to evaluate whether lipid peroxidation of the brain and cerebrospinal fluid (CSF) increased following bilateral internal jugular vein ligation and recirculation. Bilateral jugular vein ligation was performed in anaesthetised guinea pigs. Lipid peroxidation activity quantified as the thiobarbituric acid reactive material (malondialdehyde, MDA) level was assessed in the brain tissue spectrophotometrically and in the cerebrospinal fluid fluorometrically. Samples of similar contralateral brain structures were investigated with light microscopic histological techniques. Lipid peroxidation activity of the brain decreased after ligation when compared with the sham operated group, and it increased up to the control values after recirculation. On the contrary, lipid peroxidation activity of the cerebrospinal fluid increased following ligation and decreased after recirculation. These results suggested that, such an one and two hours indirect ischemic model based on increased intracerebral pressure and extravasation did not cause an increase of the lipid peroxidation, probably due to the impaired circulation resulting in low PO2 levels. However, following recirculation, there was a moderate increase of lipid peroxidation, due to increased PO2 levels. Where as MDA contents of the CSF increased following one and two hours ligation, because it couldn't transport away by the venous circulation; it decreased by two hours recirculation.