Biosensors have been developed using various types of sensing elements like biomacromolecules (viz. enzymes, antibodies, receptors, nucleic acids, etc.) organelles, tissues, intact cells of both microorganisms and higher organisms. A recent trend is the emergence of aptamers as sensing elements that has the potential to replace all the above ligands. This is possible due to the unique features of aptamers (sensitivity, specificity, reusability, stability, non-immunogenic- ity), which can be easily exploited in biosensor technology. Aptasensors are thus basically biosensors based on aptamers as ligand molecules. Here we review the various applications of aptasensors in health (specifically in diagnostics), food industry and environmental monitoring.