An oligonucleotide (m5C-am2A-m5C)5containing 2'-amino-deoxyadenosine (am2A) and 5-methyldeoxycytidine (m5C) residues has been synthesized and compared with unsubstituted pentadecadeoxyribonucleotide (CAC)5as a hybridization probe for DNA fingerprinting. It was shown that considerably higher sensitivity can be achieved with the modified analog. © 1994 Academic Press Inc.