Novel single nucleotide polymorphisms (SNPs) were found in introns 1, 3, 4, 5, and 7 of the gene encoding cytochrome (CYP) 2D6 in 90 Japanese subjects. Some of these SNPs were associated with C2850T and/or C100T, which are key SNPs for CYP2D6(*)2 and CYP2D6(*)10, respectively. The SNPs in the CYP2D6 gene (ACCESSION NUMBER, M33388) were designated as follows: SNP, MPJ6_2D6010 (IVS1-138C>G) associated with C2850T; SNP, MPJ6_2D6012 (IVS1-41T>G) associated with C100T, C2850T and G4180C; SNP, MPJ6_2D6016 (IVS3+32A>G); SNP, MPJ6_2D6017 (IVS4-17C>G); SNP, MPJ6_2D6018 (IVS4-17C>T); SNP, MPJ6_2D6020 (IVS5+46G>A); SNP, MPJ6_2D6021 (IVS5-49T>C); SNP, MPJ6_2D6023 (IVS7+40A>C) associated with both C100T, C2850T and G4180C; SNP, MPJ6_2D6024 (IVS7+64T>C); and SNP, MPJ6_2D6025 (IVS7-9C>T) associated with C2850T. These SNPs are convenient for allele typing and should be further investigated for their potential effects on transcription, such as splicing.