The majority of patients undergoing solid organ transplantation develop hypertension, to which vasoconstriction and impaired endothelial function have been suggested to contribute. We compared basal vascular resistance and nitric oxide-mediated endothelial-dependent and independent vasoreactivity between cyclosporine-treated lung transplant recipients and healthy subjects. Forearm blood flow was measured by venous occlusion plethysmography at rest and during acetylcholine, glyceryltrinitrate and N(G)-monomethyl-L-arginine acetate (L-NMMA) infusion in 11 lung transplant recipients 3-5 years after transplantation and in eight healthy subjects. Forearm vascular resistance (FVR) was calculated. Plasma levels of endothelin-1 (ET-1) and von Willebrand factor (vWf) were analysed. Basal vascular resistance was 40% lower in transplant recipients than in healthy subjects (P = 0.021). Endothelial-dependent and independent vasodilation did not differ. Plasma levels of ET-1 and vWf were higher in transplant recipients (P = 0.009 and P < 0.001 respectively). There was a significant correlation between ET-1 levels and FVR in healthy subjects (r = 0.83, P = 0.042), but not in transplant recipients (r = -0.14, P = 0.70). The findings oppose the theory of generalized vasoconstriction and impaired endothelial function in the pathogenesis of hypertension after transplantation. Increased plasma levels of ET-1 do not cause increased FVR in lung transplant recipients.