This book summarises the most recent contributions in the fabrication of carbon nanotubes- based electrochemical biosensors in recent years. It discusses the synthesis and application of carbon nanotubes to the assembly of carbon nanotube-based electrochemical sensors, its analytical performance and future expectations. An increasing number of reviews and publications involving carbon nanotubes sensors have been reported ever since the first design of carbon nanotube electrochemical biosensors. The large surface area and good electrical conductivity of carbon nanotubes allow them to act as "electron wire" between the redox centre of an enzyme or protein and an electrode's surface, which make them very excellent material for the design of electrochemical biosensors. Carbon nanotubes promote the different rapid electron transfers that facilitate accurate and selective detection of cytochrome-c, _-nicotinamide adenine dinucleotide, haemoglobin and biomolecules, such as glucose, cholesterol, ascorbic acid, uric acid, dopamine pesticides, metals ions and hydrogen peroxide.