S-adenosylmethionine decarboxylase(SAMDC : EC 4.1.1.50) is a key regulatory enzyme in the polyamine biosynthetic pathway. Numerous studies have shown that the enzyme and polyamine levels are always correlated with cellular growth in plants. animals and bacteria. In order to gain more insight into the role of the pathway in plant cells, a human SAMDC cDNA was transferred totobacco (Nicotiana tabacaim) cells. Binary Agrobacterium tumefaciens vectors containing human SAMDC cDVA attached to 35s promoter of CAMV or chalcone synthase promoter of bean (Phaseolus vulgarzs) were constructed. Plants were transformed using Agrobacterium leaf disk cocultivation method. The transformed plants were selected on 120 ㎎/ℓ kanamycin. The presence of human SAMDC cDNA was confirmed by Polymerase Chain Reaction(.PCR) and subsequent Southern hybridization. The Northern hybridization showed that the cDNA was transcribed into two different sizes of mRNAs (1.7 and 2.1 kb). Western blotting using anti-rat SAMDC antibodies showed that proteins from some of the transformed plants reacted with the antibodies. Several of the transformed plants showed increased SAMDC activity. The polyamine assays showed that in the transformed plants, putrescine level was very low while spermidine content was 2-3 times higher than control plants. Spermine content re-mained unchanged. Most of the transformed plants frequently produced shoots even on callus inducing medium. Some plants produced smaller flowers and leaves when transferred to the greenhouse.