In this study the role of circulating transforming growth factor beta1 (TGFbeta1) on progression of renal hypertensive disease has been investigated. Fifty consecutive outpatients with essential hypertension were enrolled and divided into three groups, according to their urinary albumin excretion (UAE). Group A comprised 10 hypertensives with UAE <or=20 mg/24 h (normoalbuminuric group); Group B included 21 hypertensives with UAE > 20 < 300 mg/24 h (microalbuminuric group); Group C encompassed 19 hypertensives with UAE >or= 300 mg/24 h (proteinuric group). In all patients UAE by immunonephelometric assay, circulating TGFbeta1 by a solid phase specific sandwich ELISA technique, BUN and creatinine by routine laboratory methods were determined. In addition, left ventricular telediastolic internal diameter, interventricular septum diastolic (IVSTd), posterior wall thickness, total and normalised to height(2.7) left ventricular mass, relative wall thickness and left ventricular ejection fraction by M-B Mode echocardiography were calculated. Our results indicated that TGFbeta1 levels were significantly (P < 0.05) higher in Group B and C than Group A and in Group C than Group B. In addition IVSTd values were significantly (P < 0.05) higher in both Group B and C than Group A. An evident, but not significant, higher prevalence of subjects with left ventricular hypertrophy were observed in Group C as compared with other groups. In all hypertensive subjects TGFbeta1 correlated directly with UAE (P < 0.0001) but not with BMI, LVM/h(2.7) and mean blood pressure. Our data indicated that TGFbeta1 might be considered a useful marker to evaluate the severity and progression of hypertensive renal disease. Additional long-term clinical data are needed to evaluate whether inhibition of TGFbeta1 system may prolong the time to the ESRD in hypertensive patients.