Fatty liver is one of the local morphological manifestations of metabolic syndrome and is frequently associated with insulin resistance. Insulin resistance is also common in patients with chronic hepatitis C. Hyperinsulinemia is an independent risk factor for hypertension and cardiovascular mortality. The aim of this study was to evaluate the therapeutic efficacy of angiotensin II receptor blockers (ARBs), telmisartan and olmesartan, for patients with nonalcoholic fatty liver disease (NAFLD) and chronic hepatitis C (CH-C). We analyzed the incidence of obesity, insulin resistance, and other disorders in patients with NAFLD (Group A), CH-C (Group B), or other liver diseases (Group Q. We evaluated whether the ARBs, telmisartan and olmesartan, improved insulin resistance and liver injury by measuring the homeostasis model assessment ratio of insulin resistance (HOMA-IR) and serum alanine aminotransferase (ALT). The incidence of obesity (BMI >= 25 kg/m(2)) was significantly higher in Group A than in Groups B and C. The incidence of insulin resistance (HOMA-IR >= 2.5) in Groups A and B was significantly higher than in Group C. Regular doses of telmisartan and olmesartan significantly improved HOMA-IR and ALT levels not only in NAFLD patients but also in patients with CH-C. The effects tended to be more notable with telmisartan. In conclusion, telmisartan and olmesartan improved insulin sensitivity and may possibly be used as liver protecting agents in CH-C as well as NAFLD patients.