Abstract Background Transforming growth factor-β (TGF-β) is a multifunctional cytokine that has been linked to vascular remodeling processes, myocardial hypertrophy, and renal fibrosis. Recently a correlation between serum levels of TGF-β1 and blood pressure (BP) levels in patients with end-stage renal disease was shown. In addition, it is not clear whether TGF-β1 is a causative factor in the pathogenesis of essential hypertension and associated with hypertensive target organ damage (TOD). Methods Using a TGF-β1-specific sandwich ELISA, we compared plasma levels of active and total TGF-β1 of 30 normotensive persons and 85 patients with essential hypertension with and without TOD, as measured by microalbuminuria or left ventricular hypertrophy. Results Active and total TGF-β1 levels were significantly higher in plasma of patients with essential hypertension than in normotensive controls ( P < .05 and P < .01, respectively). However, neither active nor total TGF-β1 correlated with systolic or diastolic BP (R 2 < 0.14 for all parameters). Levels of active and total TGF-β1 were significantly higher in hypertensive patients with than without TOD ( P < .05). Conclusions Active and latent TGF-β1 levels are markedly increased in plasma of hypertensive patients. We assume that TGF-β1 contributes substantially to the development of TOD in essential hypertension, independent of BP levels.