Endosulfan has proved to be a cheap and efficacious insecticide. It provides ongoing value in the protection of conventional and transgenic cotton crops against Heliothis and other Insect pests. However, endosulfan has been associated in the past with off-site residue problems that threaten its ongoing registration. There are two primary areas of concern in this regard. The first of these is with respect to environmental impacts of endosulfan contamination of downstream waterways. The second centres on concerns regarding endosulfan residues identified in locally grown beef through consumption of contamination of pastures. The cotton industry has responded to the concerns surrounding endosulfan usage by developing and achieving widespread adoption of Best Management Practices for Minimising the Impact of Pesticides. Whilst these practices should reduce the risk, the seriousness of the concern with respect to the two issues identified above requires development of mechanisms to directly address contamination. Many of the problems with endosulfan residues would be avoided if water at risk could be quickly decontaminated. This could be achieved by on-farm bioremediation of tail water with specialised enzymes (proteins that catalyse chemical reactions). This paper describes early progress in a CRDC and CRC supported CSIRO project that is working towards this goal. A more detailed description of this work will appear in Sutherland et al , 2000a, b (I, 2).