Thermodilution cardiac output and cardiac index (CI) require inserting a pulmonary artery catheter, an invasive device associated with many iatrogenic complications. The purpose of this study was to establish the concurrent validity of two noninvasive measures of CI (skin temperature and limb blood flow) by determining their correlation with invasive CI. Twenty-one subjects undergoing coronary artery bypass grafting (CABG) were studied every 2 hours for 8 hours in the immediate postoperative period. Neither limb blood flow (LBF) nor skin temperature at five sites correlated significantly (p < .05) with CI at all five data collection times. Ankle temperature and LBF were significantly correlated with CI at one data collection time. On the basis of the findings of this study, neither skin temperature nor LBF can be used as a noninvasive predictor of CI in the immediate postoperative period following CABG.