Abstract: The content and composition of main component of Silymarin in dried fruits of Silybum marianum L. Gaertn collected from different environmental conditions of Iran were analyzed by TLC and HPLC method and compared with those from Hungarian fruits. For determination of presence of flavonolignans, samples were analyzed by TLC and five bands were revealed related to silybin, isosilybin, silychristin, silydianin and taxifolin. The amount of flavonolignans was determined by HPLC method and two pairs of diasteroisomeric silybin (silybin A, silybin B, isosilybin A, isosilybin B) were separated. The results showed that silymarin amount in fruits of different areas were very different from each other and the highest amount of silymarin content were in fruits of Borazjan (south-west of Iran) and Rudbarak (north of Iran) (27.1 and 24.6 mg g-1 dry Wt.) The major flavonolignan of this sample (Borazjan) were silybin B and isosilybin B. The content of silymarin in fruits of plants that grown under greenhouse conditions (3.3 mg g-1 dry Wt.) was much lower than amount of silymarin in fruits of other areas and Hungarian fruits (22.7 mg g-1 dry Wt.).