It is becoming clear that exonic sequences can act as determinants of their own fate: the inclusion or exclusion from mature mRNA. Indeed, even silent nucleotide substitutions can cause aberrant exon skipping, resulting in a disease phenotype. It might be possible to restore essential splicing functions, lost through mutations, using molecular therapy at the RNA level. A variety of methods have been attempted, the most promising being the recent use of chimeric compounds that localize splicing-functional peptides by base complementarity.