Abstract: Shoots regenerated from hypocotyl explants of Linum usitatissimum on MSB differentiation medium under condition of light(25℃, 20001x , 12 h/d). Optimal shoot differentiation medium was MSB medium supplemented with BA 2 mg/Land IAA 0.5 mg/L,which resulted in 97% of shoot regeneration frequency.The hypocotyl explants were infected by Agrobacterium tumefaciens strain PGV 2260(pBI 121)containing NPT Ⅱ and GUSgenes,and subcultured on MSB selection medium containing kanamycin 50 mg/Lto select transformants.Then,the transformed shoots were rooted. Stable expression of GUSgene in the transformed calli and plants was confirmed by histochemical assay of the GUSactivity.The transformation frequency of flax hypocotyl was about 2%.