Stable incorporation of the nptII gene into Castanea sativa Mill. has been achieved by Agrobacteriummediated transformation. The transformation assays were performed by infecting wounded hypocotyls with a strain of Agrobacterium tumefaciens, LBA 4404 harbouring the plasmid p35SGUSINT. Although two schemes of selection were tested, many escapes were obtained. The best strategy to avoid this problem is the introduction of higher concentrations of kanamycin in the culture medium, immediately after coculture. PCR analysis showed of the selectable nptII gene integration in the plant genome. β-Glucuronidase histochemical assay revealed the expression of the uidA gene in shoots, regenerated from transformed explants.