Hevea brasiliensis anther calli were genetically transformed using Agrobacterium GV 2260 (p35SGUSINT) that harboured the B-glucuronidase (gus) and neomycin phosphotransferase (nptII) genes. B-Glucuronidase protein (GUS) was expressed in the leaves of kanamycin-resistant plants that were regenerated, and the presence of the gene was confirmed by Southern analysis. GUS was also observed to be expressed in the latex and more importantly in the serum fraction. Transverse sections of the leaf petiole from a transformed plant revealed GUS expression to be especially enhanced in the phloem and laticifers. GUS expression was subsequently detected in every one of 194 plants representing three successive vegetative cycles propagated from the original transformant. Transgenic Hevea could thus facilitate the continual production of foreign proteins expressed in the latex.