To evaluate radiant power received by infants under radiant warmers, 11 neonates (mean gestational age 32.2 weeks, mean weight 1.50 kg) were monitored. A wattmeter was used to evaluate warmer power (watts), and a thermopile placed at bed level was used to correlate warmer power to radiant power density received (mw/cm2). Warmer power ranged from 133–301 watts. A linear relationship existed between warmer power and radiant power density received (r= 0.97,p< 0.001). After establishing that radiant power delivery could be monitored with a wattmeter, this technique was used to quantitate radiant power in a small series of infants with and without a plastic shield. Radiant power density received decreased in all infants when shielded (mean 14.6–11.2 mw/cm2,/p< 0.01). This study demonstrates: (1) radiant wanner power can be monitored with a wattmeter; (2) warmer power correlates to radiant power density received; and (3) radiant power monitoring can be used to evaluate radiant power demands in specific clinical situations.