Agrobacterium tumefaciens-mediated cotyledonary- node explants transformation was used to produce transgenic cucumber. Cotyledonary-node explants of cucumber (Cucumis sativus L. cv., Eunsung) were co-cultivated with Agrobacterium strains (EHA101) containing the binary vector (pPZP211) carrying with CaMV 35S promoter-nptII gene as selectable marker gene and 35S promoter-DQ gene (unpublished data) as target gene. The average of transformation efficiency (4.01%) was obtained from three times experiments and the maximum efficiency was shown at 5.97%. A total of 9 putative transgenic plants resistant to paromomycin were produced from the cultures of cotyledonary-node explants on selection medium. Among them, 6 transgenic plants showed that the nptII gene integrated into each genome of cucumber by Southern blot analysis