Root cultures of Silybum marianum (L.) Gaertn. (Asteraceae) were established from in vitro germinated sterile plantlets. The cultures grew in hormone-free Murashige and Skoog medium. The flavonolignan content in the cultured roots was determined by HPLC using 30% acetonitrile in acidified water (0.5% phosphoric acid). The major flavonolignans produced by the cultured roots were silychristin (74.2 mg g-1 fresh weight (FW)) and silydianin (8.1 mg g-1 FW). The flavonolignan precursor taxifolin was also detected in the cultured roots (40.8 mg g-1 FW). Addition of methyl jasmonate to 7-days-old root cultures for 48 h increased the content of the produced flavonolignans and taxifolin to approximately 300% of the control cultures. Methyl jasmonate also enhanced about sixfold the accumulation of a compound identified as 3,3',5,5',7-pentahydroxyflavanone.