The purpose of this study is to evaluate the efficacy of rosiglitazone alone compared with rosiglitazone plus metformin or rosiglitazone plus losartan in the treatment of biopsy proven nonalcoholic steatohepatitis (NASH). This study was designed to answer the question: are there differences in the efficacy (as measured by histopathology and insulin resistance) of three different therapeutic modalities used to treat NASH?

Inclusion Criteria:

1. Patients between 18-70 years old
2. Negative urine pregnancy test in females
3. History of elevated liver associated enzymes (ALT > 40)
4. Liver biopsy within 1 year of screening in this study that shows histopathologic findings consistent with NASH

Exclusion Criteria:

1. ALT greater than three times normal
2. NYHA class 3 or 4 heart failure
3. Any congestive heart failure patient on insulin
4. Patients on one of the 3 study drugs within the past 3 months prior to enrollment
5. Alcohol consumption >20 gm/day in a female and > 30 gm/day in a male
6. Evidence of co-existent chronic liver disease to include viral hepatitis, Wilson's disease, autoimmune hepatitis, hemochromatosis, primary biliary cirrhosis, or primary sclerosing cholangitis
7. Serum creatinine on initial screening of greater than 1.4
8. Known hypersensitivity to rosiglitazone, metformin, or losartan
9. Known history of diabetic ketoacidosis
10. Female that is breastfeeding
11. Insulin dependent diabetic