To achieve the high level of gene expression, promoters are key elements. Patatin promoter has been used as a specific gene expression in potato tubers. Patatin is a group of glycol protein in potato tuber which is code by a multiple family genes. This protein makes up more than 40% of soluble proteins of potato tubers. Class I Promoters mainly responsible for tuber -specific expression pattern of proteins and located high amount in tuber parenchyma tissue s. The purpose of the present study is the cloning and expression assay of tuber specific promoter, patatin class I (pat1). Total DNA of the potato tissue samples was extracted and the pat1 promoter was amplified using specific primers and pfu polymerase by polymerase chain reaction (PCR). The fragment was isolated by two restriction enzymes (BamHI, HindIII) and was replaced with CaMV35S promoter in pBI121 vector. The recombinant plasmid was transferred to Agrobacterium tumefaciens LBA4404 strain using freez-thaw method. The specific expression of gus gene in potato tissue was evaluated using agro-infiltration method. The results of the this experiment confirmed the specific expression of the gene.