Anterior thigh, pretibial and midfoot surface temperatures (MFT) were measured by an infrared thermometer in 17 children after open heart surgery. Core temperature was measured by pulmonary artery thermistor and cardiac index (CI) by thermodilution. No significant relationship existed between the previous hour's urinary output (ml/m2.h) and either systemic vascular resistance index (SVRI) and CI. MFT was inversely related to SVRI (r = -5.3; p less than .0001) but not to CI. The core/peripheral temperature gradient correlated directly with SVRI (r = .38, p less than .01) and inversely with CI (r = -.28, p less than .05). There was no improvement in any of the correlation coefficients when hemodynamic variables were tested against temperature gradients from core to thigh and thigh to foot. Although these relationships are statistically significant, we conclude that they are not strong enough to be of value in predicting central hemodynamic status in children after heart surgery.