This study was conducted to obtain the transgenic Brnssica napus plants with tobacco Apase gene using the binary vector system of Agrobacteriurn fumefociens. The results obtained were summarized as follows: A repressible acid phosphatase gene of Saccharon~yces cerevisiae, pho105 was used for screening of tobacco Apase cDNA. In order to identify Apase gene in tobacco genome, Southern blot analysis was pcrformed and the Apase gcnc may be present as a single copy, or at most two or three copies, in tobacco genome. To isolate the tobacco Apase gene, tobacco cDNA library was constructed using purifed mRNA from -Pi treated tobacco root and the plaque forming unit of the library was 2.8 x $10^5$ pfu/m${ell}$, therefore the library might cover all expressed mRNAs. Using pho5 as a probe. tobacco Apase cDNA was cloned, and restriction mapping and Southern blot analysis of cDNA insert were revealed that the 3.6 kb cDNA contained tobacco acid phosphatase cDNA. Plasmid pGA695 -tcAPl was constructed by subcloning tobacco Apase cDNA into the Hind site of pGA695 with 35s promoter which can be expressed constitutively in plants. The Brassica napus cotyledonary petioles were cocultivated with the ,4 grobacteriunz and transferred to the selection medium. The transformed and regenerated plants were transplanted to soil medium. Southern blot analysis was done on the transformed plants, and it was confirmed that a foregin gene was stably integrated into the genonies of B. nnpus plants.