According to the American Academy of Pediatrics (AAP), about 60% of all newborns in the United States each year are diagnosed with jaundice, a major symptom of hyperbilirubinemia. Even though only a small percentage of these infants will have bilirubin levels that, according to the current AAP practice parameters, are high enough to require treatment, many of these infants will be treated with phototherapy (past research has associated very high bilirubin levels with brain damage). Because jaundice is unlikely to be noticed within the typical 24-hour period before discharge from the hospital, a phototherapy device that is convenient and safe for use in the home, as well as in the hospital, is desirable. In the following study, we address the performance, safety, and convenience of three fiberoptic phototherapy systems (which consist of pads and light sources), from three manufacturers, that can be used in either a hospital or the home. We also assess the advantages and disadvantages of this technology compared with those of the conventional overhead phototherapy lamps that are still commonly used. Two systems are rated Acceptable based on their light performance and are ranked equally; one system is rated Acceptable--Not Recommended because it does not provide the typical power levels obtainable with either of the other two evaluated fiberoptic systems or conventional overhead lamps. Readers are cautioned not to base purchasing or use decisions on our ratings alone, but on a thorough understanding of the issues surrounding fiberoptic phototherapy systems, which can be gained by reading this issue in its entirety. Also see the Clinical Perspective, "Hyperbilirubinemia--When and How to Treat?," for pertinent clinical background information; the supplementary articles "Uses and Limitations of Radiometers" and "Uniformity of Light" for additional technical background information; and the supplementary article "Operating Costs of Phototherapy Devices" for additional purchasing information.