We have developed a new transporter structure that provides effective delivery ofMorpholino antisense oligomers into a wide variety of tissues in living mice. This transporter comprises a dendritic structure assembled around a triazine core which serves to position eight guani-dinium head groups in a conformation effective to penetrate cell membranes. This transporter structure is conjugated to a Morpholino oligomer to form a delivery-enabled product referred to as a Vivo-Morpholino. Vivo-Morpholinos are shown to effectively enter and function within cultured cells in the presence of 100% serum using a rigorous positive test system based on correction of a defined splicing error in a pre-messenger RNA. In addition, Vivo-Morpholinos are demonstrated to enter into a wide variety of tissues in a similar positive test system in trans genic mice, as evidenced by correction of the targeted splicing error in all tissues assessed, including near-complete splice correction in the small intestine, colon, stomach, liver, kidney, and a number of muscles. Finally, Vivo-Morpholinos, which target the exon-skipping ofexon 23 harboring a premature termination codon in the mdx mouse model, effectively restore the reading frame of dystrophin and restore expression of a functional dystrophin protein.