We assessed the agreement between rectal and noninvasive temporal artery temperature measurements in infants and children. We also evaluated the temple thermometer as a screening tool for rectal fever in this age group. Finally, we compared the performance of parents with that of nurses in using the temple thermometer. The 95% limits of agreement between the difference in rectal and average temple temperature were -1.03 and +1.52 degrees C. Mean temple temperatures obtained by parents and by nurses were similar (95% limits of agreement, -0.6 degrees C to +0.7 degrees C). A maximum temple temperature cutoff of 37.2 degrees C (99.0 degrees F) distinguished children with rectal fever of > or =38.0 degrees C with 91% sensitivity and 53% specificity. A cutoff of 37.8 degrees C (100.0 degrees F) distinguished moderate rectal fevers (> or =38.5 degrees C) with 97% sensitivity and 84% specificity. A cutoff of 38.3 degrees C (101.0 degrees F) distinguished a high rectal fever (> or =39.0 degrees C) with a sensitivity of 95% and specificity of 95%. In conclusion, temple temperatures do not reliably predict rectal temperatures, but the temple thermometer can be used as an effective screen for clinically important rectal fever in children 3-24 months old. The findings do not support use of temple temperatures to screen young infants for rectal fever > or =38.0 degrees C. Temperatures obtained by parents were comparable to those obtained by nurses.