The results of contextual analysis of 25 different middle repetitive DNA sequences are presented. It was shown that each of these repetitive DNA sequences contains at least one enhancer-like structure homologous to real enhancers, as well as to their consensus. The enhancer-like structures have been also revealed in the replication origin of some prokaryote genomes. The results are discussed in the light of a possible role of middle repetitive DNA sequences in the modulation of gene expression. Some aspects of genomes' evolution, in relation to enhancers, are also considered.