Multiple genes are involved in the susceptibility to autoimmune type 1 diabetes. The immunoreceptor programmed cell death-1 (PDCD-1), an inhibitory costimulatory molecule regulating peripheral tolerance, was reported to play a role in the development of type 1 diabetes, making the human PDCD-1 gene, PDCD1, as a candidate for disease susceptibility. In this article, we sequenced all 5 exons and exon-intron junctions of PDCD1 in Japanese subjects, and found 10 sequence variants. Preliminary data suggested no association of these polymorphisms with type 1 diabetes. These sequence variants are valuable for further studies to clarify contribution of PDCD1 to susceptibility to type 1 diabetes.