Phototherapy devices (n = 63) at twelve nurseries in Nigeria were evaluated. Irradiance was measured using the BiliBlanket Meter II. Irradiance readings ranged from 0.5 to 18.4 μW/cm(2)/nm; phototherapy units varied widely, including locally made units, reconditioned machines, and modern equipment. Imported "intact" machines with all blue bulbs had higher irradiance readings than locally made devices using primarily daylight bulbs (2.5-18.4 μW/cm(2)/nm vs 0.5-4.2 μW/cm(2)/nm). The distance between infant and phototherapy units ranged from 45 to 60 cm, far exceeding the recommended distance of about 10 cm. Only 6% of the machines provided irradiance of >10 μW/cm(2)/nm. None delivered intensive phototherapy (irradiance ≥ 30 μW/cm(2)/nm). Phototherapy devices in developing countries should be assessed for irradiance, and the infant be placed at a distance of about 10 cm from the device. Phototherapy devices with adequate irradiance would reduce the need for exchange blood transfusion and the burden of acute bilirubin encephalopathy in developing countries.