A resistance index (RI) of 0.8 or higher was shown to be a strong predictor of kidney allograft and patient survival. Uncertainties persist since the intrarenal RI is closely associated with the vascular stiffness of the allograft recipient. To clarify the diagnostic value of RI further, we analyzed parameters of vascular stiffness of the recipient and intrarenal RI of the renal allograft. In a prospective study laboratory and clinical parameters, pulse wave velocity (PWV), intima media thickness (IMT) and RI were obtained in 76 kidney allograft patients. We found that the RI values significantly correlated with the PWV (p < 0.05) and the recipients age (p < 0.01) but not with the donor age and renal function. Using multiple regression analysis recipient age, PWV, pulse pressure (PP) and IMT were identified as independent factors influencing RI values. For a more correct interpretation of the RI values in renal allografts parameters of vascular stiffness such as IMT, PP or PWV should be included.