Rapid and highly sensitive methods for detecting target molecules are required to developbiomarker-based diagnoses that help medication or therapy. Thus, the development ofhomogeneous sensing methods with high sensitivity can provide the basis for detecting a biomarkerin routine diagnostics and on site. Oligonucleotide aptamers, ligands that consist of nucleic acids,have been selected for numerous targets such as proteins and small compounds, and are applicableto biosensing platforms. In particular, attractive features of aptamers enable us to construct valuablesensing methods for clinical uses without the need to use nanomaterials. Recent discoveries ofnovel signal transducing elements derived from an enzymatic and a fluorescent oligonucleotide alsoallow for the development of homogeneous aptasensors. In this review, we describe recent progressin the development of aptamer-based biosensors with high sensitivity.