In this paper, we use Kolmogorov complexity and compression algorithms to study DOS-DNA (DOS: defined ordered sequence). This approach gives quantitative and qualitative explanations of the regularities of apparently regular regions. We present the problem of the coding of approximate multiple tandem repeats in order to obtain compression. Then we describe an algorithm that allows to nd efficiently approximate multiple tandem repeats. Finally, we briefly describe some of our results. Area : DNA sequence processing.