Heat shock proteins (Hsps) are a ubiquitous feature of cells in which these proteins cope with stress‐induced denaturation of other proteins. Among the different families of Hsps, the 70 kDa family (hsp70) is the most highly conserved and has been most extensively studied. Apart from their primary role in cellular defense under stress condition, a number of studies in recent years have shown the immense potential of hsp70 in pollution monitoring using even transgenic approach both in vivo and in vitro. This article reviews the recent developments in the widespread application of hsp70 in environmental risk assessment. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:249–254, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10086