The liver has been recognized as a major target of injury in patients with metabolic syndrome and non-alcoholic fatty liver disease has even been considered the hepatic manifestation of metabolic syndrome. Pathogenesis of non-alcoholic fatty liver disease remained unclear. Interleukin-18 belonged to pro-inflammatory cytokines and previous studies showed plasma levels of interleukin-18 correlated with metabolic syndrome. There has been no report regarding plasma levels of interleukin-18 in Chinese patients with non-alcoholic fatty liver disease.A total of 46 non-alcoholic fatty liver disease patients and 46 age- and sex-matched control subjects were enrolled to compare the clinical and laboratory characteristics and plasma levels of interleukin-18, interleukin-18 binding protein, and interleukin-18/interleukin-18 binding protein ratio. Interleukin-18 and interleukin-18 binding protein were determined by commercially available enzyme-linked immunosorbent assay (Bender MedSystem, Austria, R&D Systems, Minneapolis, MN, USA, respectively).As compared with control group, patients with non-alcoholic fatty liver disease had significantly higher body mass index (p < 0.001), waist circumference (p < 0.001), total cholesterol (p = 0.001), triglyceride (p < 0.001), low-density lipoprotein cholesterol (p = 0.002), fasting sugar (p = 0.042), fasting insulin (p < 0.001), homeostasis model assessment of insulin resistance index (p < 0.001), and lower high-density lipoprotein cholesterol (p = 0.006). Patients with non-alcoholic fatty liver disease had significantly higher interleukin-18 (340.10 +/- 43.13pg/mL) and interleukin-18/ interleukin-18 binding protein ratio (1.31 +/- 0.12) compared with control group. Nonalcoholic fatty liver disease patients with abnormal alanine aminotransferase had higher plasma interleukin-18 (352.60 pg/mL) than non-alcoholic fatty liver disease patients with normal alanine aminotransferase but did not reach the statistical differences.Through the chemotactic and proinflammatory effects, interleukin-18 may play a role in the pathogenesis of non-alcoholic fatty liver disease in Chinese patients, and it is reasonable to take into account interleukin-18 binding protein when evaluating the effect of interleukin-18.