Benign thyroid disorders are strong risk factors for non-medullary thyroid cancer (NMTC). Germline variation in Tg (thyroglobulin) and TSHR (thyroid stimulating hormone receptor) confers an increased risk of benign thyroid disorders. To explore the hypothesis that polymorphic variation in these genes affects the risk of NMTC we compared the frequency of TgQ2511R, TSHR-P52T and TSHR-D727E genotypes in two series of NMTC cases and controls (group 1, Canadian 102 cases and 102 controls; group 2, British 202 cases and 298 controls). No significant association was seen with TSHR-P52T and TSHR-D727E genotypes and risk of NMTC. However, the frequency of the R-allele of TgQ2511R was over represented in NMTC cases in both study populations. The odds ratios associated with hetero- and homozygosity for the R-allele were 1.6 (95% confidence interval, 1.1-2.5) and 2.0 (95% confidence interval, 1.2-3.3), respectively. Although the risk of NMTC associated with the TgQ2511R R-allele is modest, its high prevalence in the general population suggests it may make a significant contribution to the incidence of NMTC.