BACKGROUND:– Accurate measurement of temperature is important in detecting fever and hypothermia in neonates. Hypothermia is an important contributor for neonatal morbidity and mortality in developing countries. Rectal temperature measurement is the gold standard measurement. We studied the correlation and agreement between Axillary, Infrared Tympanic and Infrared Forehead temperature measurement with Rectal temperature measurements, in sick newborn babies at different time intervals newborn emergency room. METHODS:– This is an observational study, where temperature measurement were takenfrom rectal site first with digital thermometer, followed by Axillary temperature with digital thermometer, both tympanic and forehead temperature measurements using the Infrared thermometer at 5 minutes, 15 minutes, and 30 minutes from the time of arrival to the Newborn emergency room at Institute of Child Health and Hospital for Children, Chennai. The digital axillary, infrared tympanic and infrared forehead temperature measurements were compared with digital rectal temperature measurements, which is the gold standard temperature measurement.Certain subgroup analysis were done; neonates with low birth weight, Gestational age 32–36 weeks, Gestational age >36weeks, Normothermic babies, Hypothermic neonates, Hyperthermic neonates, neonates with seizures, respiratory distress and shock. The Pearson Correlation Coefficient(r) and the Bland–Altman Plot Analysis for agreement were obtained. RESULTS:– A total of 600 measurements were taken from 200 neonates attended the emergency room within the study period. The infrared tympanic temperature measurement showed highest positive correlation when compared with rectal temperature measurement (r=0.851, p<0.0001). Axillary temperature measurement also showed good correlation(r=0.759, p<0.0001) but is inferior when compared with tympanic measurement. Infrared tympanic measurement also has strong agreement with rectal temperature measurements (Mean difference 0.311, CI 0.339, 0.284). Highest correlation shown by infrared tympanic measurements is sustained in small, sick and normal neonates; Hypothermia (r=0.872, p<0.0001), Hyperthermia(r=0.931, p<0.0001), shock(r=0.944, p<0.0001), Low birth weight–1500 to 2500 grams (r=0.852, p<0.0001), Gestational Age–32 to 36 weeks(r=0.815, p<0.0001), Gestational Age>36 weeks(r=0.854, p<0.0001). Right and left infrared tympanic measurements correlated well with each other(r=0.921, p<0.0001) and right tympanic measurements correlated well with rectal temperature measurement(r=0.851, p<0.0001). Forehead temperature measurement showed poor correlation with rectal temperature measurement. CONCLUSION:– Infrared Tympanic temperature measurement is the most reliable method of temperature measurement in neonates. Tympanic and axillary temperature measurements are reliable in sick, small (>32 weeks and >1500 grams) and healthy neonates.