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 760 nm) reflected by the skin.