During the last three decades, numerous biological techniques have been developed as qualitative analytical methods to assess the effects of chemical pollutants on the environment, but only in the last 10 years have these methods been widely integrated into pollution-control programs.The increasing number of potentially harmful pollutants in the environment calls for fast, cost-effective analytical techniques to be used in extensive monitoring programs. As a result, the use of biological data to complement chemical analysis as well as the development of bio-detectors, such as immunoassays, biosensors and bioassays, has grown steadily in recent years.This overview article describes the principles, advantages and limitations of several biological methods for screening and diagnosis of organic compounds in environmental samples of water, sludge and sediments. It also describes the valuable and additional biological type of information that can be obtained through these determinations.This overview aims to describe the state of the art in Europe on sensors, biosensors, bioassays and immunochemical techniques for monitoring of water and soil pollution, with special attention to the screening methods developed under the European Commission’s 4th and 5th Framework Research Programs [1994–1998 (FP4) and 1998–2002 (FP5)].