This is a multicenter, randomized, double masked, placebo controlled Phase II trial to evaluate the safety and explore the efficacy of silymarin (Legalon®) compared with placebo on hepatic histology in patients with NASH (nonalcoholic steatohepatitis) after 48-50 weeks of therapy. This study was originally sponsored through a cooperative agreement (U01) award from the NCCAM and the NIDDK (RFA-AT-05-006: "Phase I/II Trials of Silymarin for Chronic Liver Diseases"), and now will continue with Madaus Inc. (Rottapharm Group) providing financial and regulatory support to the investigators. The broad aim of this study is to evaluate the safety and explore the efficacy of silymarin (Legalon®) in NASH patients and to form the basis for future studies which will establish its efficacy for treating patients with NASH. The specific objectives of this study are to determine the effect of silymarin (Legalon®) on the histologic NASH Activity Score (NAS), the liver enzymes, and HOMAr. The primary endpoint of the study is an improvement in the NAS by at least 2 points. Various secondary endpoints will be assessed, including the change in liver enzymes and HOMAr.