Tacrolimus and cyclosporin A (CsA), the mainstay of preventive therapy for solid organ rejection, may cause various side-effects, such as hypertension and nephrotoxicity. Furthermore, tacrolimus is associated with cardiac hypertrophy. In the immediate post-transplant period, both drugs raise the levels of Endothelin-1 (ET), a potent vasoconstrictor; and of B-type Natriuretic Peptide (BNP), a sensitive marker of left ventricular volume overload, which may precede echocardiographic changes of cardiac dysfunction. The aim of the study was to investigate the presence of cardiac damage, by echocardiography and by the biochemical markers BNP and ET, in post-orthotopic liver transplantation (OLT) children, receiving long-term immunosuppressive therapy. ET (ELISA) and BNP (RIA) were measured in plasma of 18 children, post-OLT and 18 healthy controls. Children post-OLT were echocardiographically assessed for left ventricular mass (interventricular septum and posterior wall dimensions), systolic function (ejection fraction, fractional shortening) and diastolic parameters (mitral valve E and A waves, deceleration time, isovolumic relaxation time). None of the post-transplant recipients had a history or physical examination consistent with cardiac disease and all recipients were normotensive. Echocardiography revealed no systolic or diastolic dysfunction in any of the recipients. The mean ET and BNP levels tended to be higher among children post-liver transplant, compared with healthy controls (ET: 4.22 +/- 5.35 pg/mL vs. 2.1 +/- 2.0 pg/mL; BNP: 7.05 +/- 4.4 pg/mL vs. 5.87 +/- 2.0 pg/mL, respectively, mean +/- s.d.) although differences did not reach statistical significance. Three children (17%) had elevated BNP and/or ET levels. A strong correlation was observed between ET and BNP levels in post-OLT children (r = 0.79, p < or = 0.05). No correlation was found between ET or BNP levels and echocardiographic findings. In children receiving long-term immunosuppressive therapy post-OLT, although cardiac function is grossly preserved, ET and BNP levels tend to be higher than in healthy, age-matched children. Thus, elevated levels of BNP and/or ET may identify patients with early cardiac damage.