Abstract: There is disclosed a method for determining the identity of one or more mutations or single nucleotide polymorphisms (SNPs) in a genome, comprising: a contacting a sample genome, under conditions which permit template dependant oligonucleotide ligation, with a plurality of different oligonucleotide molecules which comprise (i) a first set of oligonucleotides each comprising a sequence of nucleotides that is complementary to a region on said genome that includes a known SNP site and which oligonucleotides are complementary to said region other than at a base at or near the 5? end of said oligonucleotides that is to be tested for complementarity to a base at the SNP site, each of said oligonucleotides comprising a unique label to identify both the base to be tested and the position of the SNP to be scored, (ii) a second set of oligonucleotides each comprising a sequence of nucleotides complementary to a region on said target genome for hybridisation with said target genome adjacent the 5? end of an oligonucleot