Electrochemical sensors for multiple analytes were the first scitifically proposed as well as commersialised biosensors. Electrochemical biosensors have been studied for a long time. Presently, typical platform of transducers based on semiconductors and screen printed electrodes is in practice for construction of biosensors. Among all biocomponents enzymes or enzyme labeled antibodies are presently the most common biorecognition tools used in biosensor. This review highlights the principle and some typical applications for the electrochemical biosensors. These have been categorized in three categories based on their operation and application as: potentiometric, amperometric and impedimetric transducers. The review also highlights some of the most typical assays used.