Background: Recent data from a population-based study in children and adolescents suggests that serum thyroid-stimulating hormone levels (TSH) are associated with arterial blood pressure and hypertension. These results are in agreement with some, but not all population-based studies in adults. Discrepancies in results might be explained by drug intake, different iodine supplies and sizes of populations investigated. In addition, it is not clear, whether an association between TSH and hypertension exists longitudinally rather than only cross-sectionally. Thus, our aim was to investigate cross-sectional and longitudinal associations between thyroid function and arterial blood pressure in a large consortium of cohort studies in adults. Methods: Data from five population-based studies were pooled resulting in 17,023 individuals being available for cross-sectional and 10,048 individuals for longitudinal analyses. Associations of baseline TSH with baseline blood pressure or hypertension were analyzed by multivariable median or logistic regression models. Multivariable median or Poisson regression models were used to investigate associations of baseline TSH with 5-year-change in arterial blood pressure or incident hypertension. Results: There was a cross-sectional positive association of TSH with arterial blood pressure (p