Myotonic dystrophy (DM) is the most common form of muscular dystrophy in adults, which is caused by unstable genomic expansions of CTG or CCTG repeats. Mutant RNA transcripts containing the expanded repeats cause toxic gain-of-function by perturbing splicing factors in the nucleus, resulting in misregulation of alternative pre-mRNA splicing. Recent advances in basic and translational research and pharmacological approaches have provided clues for therapeutic intervention in DM. Herein, we review the RNA-dominant mechanism of DM and therapeutic approaches for targeting the toxic RNA.