We have analyzed a mutation responsible for a Hinf I polymorphism of the D1S80 system by Taq dye deoxy terminator cycle sequencing. A G-T transversion at the 58th nucleotide from the 5' end of the forward primer was identified. This mutation has been firmly established by the restriction enzymes. The type G was digested with Hinf I but not with Tsp 509 I. Conversely, the type T was digested with Tsp 509 I but not with Hinj I. We applied this technique to analyze D1S80 system in German and Japanese populations. In the Japanese population, the type T frequencies were much lower than those in the German population, and the type T was almost exclusively observed in the allele 24.