Background: Hepatitis C virus infection is characterised by enhanced oxidative stress, which can be measured quantitatively by plasma oxysterol concentration. These molecules may affect lipid metabolism through the activation of Liver X Receptors. Hepatitis C virus exploits host lipid metabolism to facilitate its replication and diffusion. In our study we aimed to evaluate and highlight the potential pathogenetic role of oxysterols, 7-ketocholesterol and 7-beta-hydroxycholesterol, in hepatitis C virus-related lipid dysmetabolism. Methods: The study was performed in 42 patients with chronic hepatitis C (93% genotype 1b) and 38 nonalcoholic fatty liver disease patients. Plasma oxysterols 7-ketocholesterol and 7-beta-hydroxycholesterol were determined by isotope dilution gas chromatography/mass spectrometry. Results: Gas chromatography/mass spectrometry revealed higher 7-ketocholesterol (71.2 +/- 77.3 vs 30.4 +/- 14.5; p