We have developed new artificial oligonucleotide probes that show selective recognition for short RNA targets over long RNA targets. Our results suggested that modification of the termini of the oligonucleotide probes by bulky substituents such as cyclohexyl and 4-(3,6,9-trioxaundecylenedioxy)phenyl (Bzcr) groups significantly improved the selectivity of the probes toward the short RNA targets. The