Recent progress in DNA technology, such as antisense oligodeoxynucleotides (ODNs) to regulate the transcription of disease-related genes, has important roles in therapeutic applications. Recently, transfection of cis-element double-stranded DNA, named as 'decoy', has been reported to be a useful method for gene therapy. This 'decoy' strategy has been not only a useful method for the experimental studies of endogenous gene regulation but also a novel clinical strategy for gene therapy. In this article, we reviewed (1) experimental results from the several disease models, (2) the ongoing clinical trials including coronary angioplasty, arthritis, and dermatitis in Japan.