This review provides an introduction to the field of thin films formed by Langmuir–Blodgett or self-assembly techniques and discusses applications in the field of biosensors.The review commences with an overview of thin films and methods of construction. Methods covered will include Langmuir–Blodgett film formation, formation of self-assembled monolayers such as gold–thiol monolayers and the formation of multilayers by the self-assembly of polyelectrolytes. The structure and forces governing the formation of the materials will also be discussed.The next section focussed on methods for interrogating these films to determine their selectivity and activity. Interrogation methods to be covered will include electrochemical measurements, optical measurements, quartz crystal microbalance, surface plasmon resonance and other techniques.The final section is dedicated to the functionality of these films, incorporation of biomolecules within these films and their effect on film structure. Species for incorporation will include antibodies, enzymes, proteins and DNA. Discussions on the location, availability, activity and stability of the included species are included.The review finishes with a short consideration of future research possibilities and applications of these films.