A resveratrol synthase gene was cloned from the peanut plant (Arachis hypogaea) by RT-PCR and was transformed into purple sweet potato (Ipomoea batatas) by Agrobacterium-mediated transformation. Stem sections were infected with bacterial solution of OD(600) = 0.4 for 20 min and then cocultured for 2 days. Infected explants were cultured on MS media containing 50 mg/l kanamycin, 0.02 mg/l NAA and 1 mg/l 6-BA for bud induction or containing 75 mg/l kanamycin, 1.0 mg/l NAA and 0.1 mg/l 6-BA for root formation. The bud and root induction rates were 37.5 and 25.0%, respectively. 105 regenerated plants were obtained, with 11 positive plants by PCR and Southern blotting analyses. A high level of resveratrol glucoside (340 mu g/g dry weight), but no resveratrol, was detected in the transformed plants by HPLC. This study also provides a stable genetic transformation and plant regeneration method for metabolic modification of purple sweet potato.