Biosensors are a very important subject in the contemporary analytics, mainly in biomedical area. This chapter describes biosensors built with the use of conductive polymers. Conductive polymers provide electrical conductivity of the forming layer, they may function as mediators in red-ox processes and they can enable the immobilization of a biological agent on their surface. Nowadays, in the center of attention are composite materials in which, next to conductive polymers, nanostructured materials such as graphene, carbon nanotubes and quantum dots are applied. In the chapter, the basic modes of biosensors of the first, the second and the third generation, are described. The examples of different enzymatic and affinity biosensors are presented.