Legumes have long been recalcitrant to efficient Agrobacterium tumefaciens -mediated transformation. The choice and use of model legume plants (Medicago truncatula and Lotus japonicus ) for molecular studies has triggered extensive studies devoted to the development of efficient Agrobacterium -mediated transformation protocols for these two plants. In M. truncatula , transformation protocols rely on the use of highly regenerable lines obtained by recurrent in vitro culture selection. These protocols are based on Agrobacterium -mediated transformation of M. truncatula followed by somatic embryogenesis-mediated plant regeneration. We describe here the protocol developed for M. truncatula R108-1 (c3).