Abstract: The invention relates to methods for determining sequence information in polynucleotides by combining the recent disparate technologies of mass spectrometry and polynucleotide hybridization, amplification, extension and/or ligation techniques. Broadly, in a first step, the method for determining sequence information in a sample polynucleotide includes hybridizing with a sample nucleotide one or a mixture of oligonucleotide probes having a nucleotide sequence complementary to a portion of the sample polynucleotide, thereby forming a complex. Then, in a second step, the complex is contacted with at least a member selected from the group consisting of nucleosides, dideoxynucleosides, polymerases, nucleases, transcriptases, ligases and restriction enzymes to alter at least a subset of said oligonucleotide probes.