Background: Silymarin complex consisted of five flavonolignans (silybin A & B, Isosylibin A & B, silychristin, silydianin and taxifolin) isolated from dried fruiets of Silybum marianum (L.) Gaertn. Silybin is the main component of silymarin complex. Hepatoprotective activeity of silymarin may related to its antioxidant property. Objective: This study was conducted to understand the environmental condition on silymarin methabolism. Methods: Silymarin extraction and flavolignans assay by spectrophotometery, TLC and HPLC was performed on Milk thistle seeds collected from different areas of Iran, Hungarian seeds cultivated in greenhouse and field in karaj. Results: Valasht and Borazjan had the highest levels of silymain content by spectrophotometery method. In TLC method all 5 components were identified. We analyzed the flavolignans contents by HPLC and results showed that Borazjan had the highest level of silymarin. Conclusion: To produce commercially silymarin we need to search for the best genotype.