the level and stability of transgene expression can be influenced by factors such as structure of expression cassette, integration pattern and locus structure. The structure of transgene locus is important in its expression mechanisms. The aim of this experiment was to characterize the cry1Ab transgene locus structure in a transgenic rice (Oryza sativa, cultivar Tarom Molaii). This transgenic rice, co-transformed with two different plasmids (pCIB4421 and pChitIHygII), had a simple integration pattern and stable expression over several generations. In order to characterize the cry1Ab transgene locus stracture, the exact insertion site was identified using specific primers corresponding to 3´ and 5´ ends of ampR gene, 3´ end of cry1Ab gene and 5´ end of PEPC promoter on pCIB4421 plasmid. Then, DNA sequences of the flanking insertion sites were amplified using two methods of one-side PCR including TAIL-PCR and Splinkerette PCR. Sequencing of the PCR products and bioinformatics analysis revealed that pCIB4421 plasmid break for insertion was 148 bp after 3´ end of ampR gene. A fragment corresponding to 1499bp downstream sequences and 311 bp upstream of insertion site were isolated. BLAST search was performed against the pCIB4421, the pChitIHygII and Oryza sativa genome. Downstream sequences of the insertion site was scrambled fragments of delivered DNA and rice genome, however the upstream of the insertion site was non-continuous fragments of the delivered DNA.