According to WHO report, cancer is one of the leading reasons of human death worldwide, accounting for around 13% of all deaths (7,6 million all deaths)[1]. One of the causes is late diagnosis of cancer. Recently, biosensors seem to be a good solution to help solve that problem. Biosensors are devices consisting of two components: a biological one, which reacts with analyzed substance, and an analitical component, which generates and transduces the signal. The paper is discussing about the most popular biosensor types and the way they work. It also shows examples of use, with impact on perspectives concerning cancer diagnosis.