We performed a clinical trial of a new tympanic thermometer to test its accuracy in a pediatric emergency department. Tympanic temperature was compared to oral or rectal glass and electronic temperature, depending on the developmental age of the child. Results were controlled for age of the child, cooperation, quantity of cerumen, and the presence or absence of otitis media. Our results suggest good correlation of tympanic with oral and rectal glass thermometry except in infants less than three months of age. Sensitivity and specificity, respectively, were 80% and 93% for detecting fever of 38 degrees C and 80% and 95% for detecting fever of 38.5 degrees C.