A protocol is described for the simple, rapid and efficient production of transgenic Arabidopsis plants. The procedure was developed using growth regulator regimes that promote adventitious embryogenesis during or immediately following Agrobacterium mediated transformation. Both the RLD and Columbia genotypes of Arabidopsis were transformed using slightly different growth regulator regimes. For the Columbia genotype two modifications of the protocol were identified which substantially improved regeneration. Cold treatment of the plants used as a source of root explants resulted in a three-fold increase in the number of morphogenic sectors produced. A more important modification was the inclusion of 25 mg/l silver nitrate (an inhibitor of ethylene action) to the medium used for shoot regeneration. This provided a ten-fold increase in the number of shoots produced. These procedures made it possible to obtain over 100 putative transformants of RLD or Columbia from a single 10 cm petri dish, within 2 or 4 weeks after exposure of root explants to the bacteria. When these were transferred to rooting media containing antibiotics, approximately 20% were able to root after kanamycin selection and 80% after hygromycin selection. All the rooted plantlets tested were shown to contain integrated donor DNA as determined by Southern blot analysis.