Metabolic syndrome (MetS) is characterized by the presence of atherogenic risk factors, and is associated with a marked increase in the risk of cardiovascular disease. Recently, the criteria of MetS were newly defined in Japan. We examined the relationship between MetS and the various metabolic parameters in Japanese subjects. This study included 458 Japanese subjects undergoing medical checkups at Nagoya University Hospital. New criteria developed by the joint committee of eight Japanese medical societies for the clinical recognition of MetS were adopted. We examined the association between MetS and various metabolic parameters, including liver enzymes (alanine aminotransferase, ALT; gamma glutamyltransferase, GGT) and highly sensitive C-reactive protein (hsCRP). The mean overall prevalence of MetS was 8.7% (male: 12.9%; female: 2.2%, p = 0.0001). MetS was significantly associated with elevated ALT (> 45 IU/L) (OR: 3.37, 95% CI: 1.19-9.52, p < 0.05) and GGT (> 64 IU/L in males, > 45 IU/L in females) (OR: 4.96, 95% CI: 2.31-10.66, p = 0.0001), respectively. MetS was also significantly associated with elevated hsCRP (> or = 0.1 ng/mL) (OR: 2.77, 95% CI: 1.20-6.41, p < 0.05). Thus, MetS was associated with elevated liver enzymes (especially, GGT), and inflammation (hsCRP).