Epidemiologic studies have shown an association between the intake of dietary fibres and 2-h glucose values. Food rich in dietary fibres is often also rich in thiamine. Animal studies have shown that thiamine deficiency can induce glucose intolerance. Our aim was to investigate the association between fibre consumption and thiamine intake on the one hand and glucose tolerance on the other hand. We used data from the Hoorn Study, a study of glucose tolerance among 1008 men and 1188 women, aged 50-75 years, without diabetes. In linear regression analyses, fibre intake was inversely associated with fasting glucose. There was also an inverse association between fibre intake and 2-h glucose but it disappeared for the greater part after adjustment for fasting glucose. Fibre intake appeared to be strongly correlated with thiamine intake, and this correlation explained the remaining part of the association between fibre intake and 2-h glucose. Thiamine intake appeared to have a strong and relevant association with 2-h glucose, which was independent of fibre intake and fasting glucose. This association was borderline after adjustment for potential confounders. In women, but not in men, the effect of thiamine intake, independent of potential confounders. In conclusion, part of the association between fibre intake and glucose tolerance is possibly attributable to concomitant thiamine intake.