The development of cost-effective on-site methods for environmental monitoring is instrumental to managing risks posed by environmental contamination. Biosensors show the potential to complement both laboratory-based and field analytical methods for environmental monitoring. Although a wide range of biosensors have been reported for potential environmental applications, relatively few of these have progressed into commercial markets. Advances in areas such as toxicity-, bioavailability-, and multianalyte-screening, and incorporation as detectors in chromatographic systems could possibly widen the market and allow these techniques to be more competitive.