This chapter will focus on techniques that have been developed to measure transcutaneous bilirubin (TcB). The first electronic TcB device proved to be useful when used as a screening method for identifying newborns who needed a serum bilirubin determination. Newer TcB devices can be used not only as screening tools but also as reliable substitutes for serum bilirubin measurements. The Chromatics Colormate III™ is still based on the colour of the skin, estimating serum bilirubin from skin-reflectance (skin colour) whereas the BiliCheck™ measures transcutaneous bilirubin by utilizing the entire spectrum of visible light (380 to 760nm) reflected by the skin.