The detection of oligonucleotides hybridized to a planar, plastic substrate using matrix-assisted laser-desorption time-of-flight mass spectroscopy is reported. Oligonucleotides of length 18 to 29 bases were hybridized to a plastic surface upon which a monolayer of an oligonucleotide of sequence 5’-TCC TCT CTC CGT CAT GCG TAT CGT TCA AT-3’ was tethered at the 3’ end. The target olignucleotides were hybridized from dilute aqueous solution. The system was prepared for laser desorption by using the matrix 3-hydroxypicolinic acid, deposited at 45 degrees C. The subsequent mass spectra revealed parent molecular ion for the target DNA with low-level dimerization and no discernible fragmentation.