Applications of biotechnological tools, including genetic modification aimed at combating Dutch elm disease, are described. In vitro shoot cultures of Ulmus procera (English elm) SR4, U. glabra, U. americana, and U. parvifolia have been established and used as source material in genetic transfer experiments. Biolistic transformation of U. procera leaf material with cauliflower mosaic virus 35S-promoted constructs resulted in transient gusA (β-glucuronidase) expression. Subsequently, regenerant U. procera have been obtained following transformation of stem pieces with wild-type tumor-inducing or root-inducing plasmid-harboring Agrobacterium strains. Genetically modified elms expressing gusA, gfp (green fluorescent protein), and nptII (neomycin phosphotransferase II) genes have been produced using disarmed vectors. Regenerant English elms have been produced following transformation with anti-fungal genes, transferred to soil, and are currently being tested for their ability to resist the Dutch elm disease fungus Ophiostoma novo-ulmi. Future prospects for fighting this fungal wilt using biotechnological tools are discussed.