We have investigated the effect of some potential chemical, photochemical, biological and environmental conditions upon the degradation of fenthion in laboratory and field experiments. These experiments have been designed with an emphasis on possible environmental situations into which fenthion might be introduced. This study also included comparisons of fenthion disappearance rates when applied to natural waters of different water quality. ; This manuscript is an author version with the final publication available at http://www.springerlink.com and may be cited as: Wang, T. C., Kadlac, T., & Lenahan, R. A. (1989). Persistence of fenthion in the aquatic environment. Bulletin of Environmental Contamination and Toxicology, 42(3), 389-394. doi:10.1007/BF01699965 ; Florida Atlantic University. Harbor Branch Oceanographic Institute contribution #659.