On the basis of the nature of nucleic acids and recent research achievements or findings about the macromolecuies, such as DNA-replication-repressor RNA, transcription-factor RNA,extracellular "communicator RNA ", ribozyme, gene shears, RNA editing, anti-virus and anti-tumor activities of antisense RNA, a new hypothesis, antisense RNA network, is advanced. i. e. There are many kinds of small antisense RNAs and their complementary antiantisense RNAs from genomic DNA within the organism. Because of self-modification (or other mechanism)，the antisense RNAs and the anti-antisense RNAs base-pair. but do not reanneal or hybridize with each other. This antiseuse RNA network, on the one hand, participates in regulating the expression of certain genes in particular tissues at particular time. keeps relative balance of various functional activitics. On the other hand, the network plays an important role in specifically recognizing and eliminating the nucleic acids mutated within the body or invaded into the body from the outside.