We have identified aptamers (synthetic oligonucleotides) binding to the very small molecule ethanolamine with high affinity down to the low nanomolar range. These aptamers were selected for their ability to bind to ethanolamine immobilised on magnetic beads, from an 96mer library of initially about 1 x 10(16) randomised ssDNA molecules. The dissociation constants of these aptamers range between K(D)=6 and K(D)=19 nmol L(-1). The aim of the development of ethanolamine aptamers is their use for the detection of this substance in clinical and environmental analysis. Ethanolamine is associated with several diseases. Moreover, ethanolamine and its derivatives di- and tri-ethanolamine are used in chemical and cosmetic industries. The use of biosensors with ethanolamine aptamer as new molecular recognition element could be an innovative method for an easy and fast detection of ethanolamine.