Studies on Agrobacterium-mediated transformation in 3 Liliaceous ornamental plants, Lilium formosanum, Agapanthus praecox ssp. orientalis and Muscari armeniacum, were described. Three different strains of A. tumefaciens were used, all of which harbored the binary vector carrying the nptII, hpt and gus-intron genes in the T-DNA region. For L. formosanum, no transgenic tissues nor plants were obtained after co-cultivation of organogenic calli with A. tumefaciens, although transient expression of the gus gene could be detected in the calli during co-cultivation. On the other hand, several hygromycin-resistant (Hyg^r) cell clusters were obtained for both A. praecox ssp. orientalis and M. armeniacum following the transfer of co-cultivated embryogenic calli onto hygromycin (Hyg)-containing media. Hyg^r calli developed into complete plants via somatic embryogenesis, and most of them were confirmed to be transgenic plants based on GUS histochemical assay and PCR analysis. Southern blot analysis revealed the integration of 1 to 5 copies of the transgene into the genome of the transgenic plants of both 2 species, but most of them had 1 or 2 copies. Agrobacterium-mediated transformation systems developed for A. praecox ssp. orientalis and M. armeniacum may be useful as a tool for their genetic improvement as well as molecular biology studies.