While most microbes play an important role in nature, certain potentially harmful microbes can contaminate food and water, and cause a plethora of infectious diseases in both animals and humans. Conventional methods for detecting microbial contamination have primarily relied on time-consuming enrichment steps, followed by biochemical identification, having a total assay time of up to I week in certain cases. Over the last decade, a great deal of research has focused on the development of biological sensors for the detection of micro-organisms, allowing rapid and "real-time" identification. This paper reviews some of the most commonly used biosensor systems based on their transducer properties, which include surface plasmon resonance (SPR), amperometric, potentiometric, and acoustic wave sensors and their applications for the detection of pathogens in food and water. It also highlights some of the limitations of applying biosensors for the detection of pathogens, such as sensitivity, cost and the need for sample pre-treatment.