PD-1 receptor is a co-signaling molecule with an important role in regulation of T-lymphocyte activity. Correlation between PD-1 gene (PDCD1) polymorphisms and some immune-related diseases has been reported before. In current study, we aimed to investigate the association of PD-1 polymorphisms at positions +7146 G/A (PD-1.3) and +7785 C/T (PD-1.5), as well as the emerged haplotypes with susceptibility to thyroid carcinoma.