Aims: Selenium is an antioxidant micronutrient with potential associations with hypertension. Few studies have investigated the association of serum selenium concentrations with blood pressure and hypertension in countries with low dietary selenium intake such as Germany, with inconsistent findings. Methods: We undertook a cross-sectional analysis of participants in the Lipid Analytic Cologne (LIANCO) cohort. To reduce potential confounding, we restricted the analysis to 792 participants who were never smokers, who did not use antihypertensive medications, and who did not have diabetes or known atherosclerotic disease. Hypertension was defined as blood pressure at least 140 and/or at least 90 mmHg. About half of the cohort was diagnosed as hypertensive. Selenium was measured by inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS). Results: Mean +/- standard deviation (SD) serum selenium concentration was 68 +/- 32 mu g/l. The multivariable adjusted differences (95% confidence intervals) in blood pressure levels comparing the highest (>91.9 mu g/l) to the lowest (<= 42.8 mu g/l) quartile of serum selenium were 5.2 (1.4 to 8.9), 2.8 (0.7 to 4.8), and 2.4 (-0.4 to 5.2) mmHg for systolic, diastolic, and pulse pressure, respectively (P for trend for all <0.003). The corresponding multivariable adjusted odds ratio for the presence of hypertension was 1.52 (0.98 to 2.36; P trend = 0.004). Conclusions: The data suggest that even in a population with very low serum selenium concentrations higher serum selenium concentrations are associated with higher blood pressure levels and a higher prevalence of hypertension. These findings call for careful evaluation of the effects of selenium on blood pressure endpoints in randomized clinical trials.