We found five novel nonsynonymous polymorphisms of the human CYP1A1 gene from Japanese individuals. The five single nucleotide polymorphisms (SNP) in exon 7 (2346_2347 ins T, 2414T>A, 2461C>T, 2500C>T and 2546C>G causing premature stop codon, Ile448Asn, Arg464Cys, and Arg477Trp and Pro492 Arg, respectively) were as follows:SNP, 030212Saito001; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5′-GTCAACCCATCT–/TGAGTTCCTACCT-3′.SNP, 030212Saito002; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5′-GTGAGAAGGTGAT/ATATCTTTGGCAT-3′.SNP, 030212Saito003; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5′-GAGACCGTTGCCC/TGCTGGGAGGTCT-3′.SNP, 030212Saito004; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5′-ATCCTGCTGCAAC/TGGGTGGAATTCA-3′.SNP, 030212Saito005; GENE NAME, CYP1A1; ACCESSION NUMBER, X02612; LENGTH, 25 base; 5′-TGGACATGACCCC/GCATCTATGGGCT-3′.