Abstract: Since the development of the glucose sensor by Clark and Lyons in 1962, generally recognized as the first biosensor, many types of sensors have been developed in which the physical or chemical transducer is provided with a layer containing a biological sensing element. The resulting device is called a biosensor, aimed to produce an electronic signal as a function of the concentration of chemical or biochemical constituent. Among many proposed concepts, the integration of biolgically active materials with a silicon chip is one of the most intriguing approaches. The silicon chips are usually designed as membranes, which have limited sensitivity. The microcantilever is an extremely sensitive device, which has attracted much attention during recent years. In this paper, the newest development of cantilever-based biosensors are summarized. The design and principle of microcantilevers together with examples of a few newly developed bio-sensors are discussed.