Fertile transgenic plants of peanut (Arachis hypogaea L. cv. New Mexico Valencia A) were produced using an Agrobacterium-mediated transformation system. Leaf section explants were inoculated with A. tumefaciens strain EHA105 harboring the binary vector pBI121 containing the genes for β-glucuronidase (GUS) and neomycin phosphotransferase II (NPTII). Approximately 10% of the shoots regenerated on selection medium were GUS-positive. Five independent transformation events resulted in the production of 52 fertile transgenic peanut plants. On average, 240 d were required between seed germination for explant preparation and the production of mature t1 seed by T0 plants. Molecular analysis of transgenic plants confirmed the stable integration of the transgenes into the peanut genome. GUS expression segregated in a 3∶1 Mendelian ratio in most T1 generation plants.