Following a screening visit, patients with histologically confirmed NASH will be randomized to either placebo or one of two active treatment groups of silymarin (Legalon®). One active treatment group will receive 420 mg, each dose given three times daily, the other active treatment group will receive 700 mg, each dose given three times daily. Patients will be treated for 48-50 weeks. Participation in this research study requires the patient to travel to the clinic for at least 11 visits so recruitment will be limited to a geographically restricted area around participating clinical centers. Liver biopsy must be performed up to 12 months prior to, and immediately after, the treatment phase.