We surveyed mercury concentrations of aquatic macroinvertebrates collected from fishless ponds on the Lyndon B. Johnson National Grassland, Wise County, Texas. Macroinvertebrates representing eight taxonomic groups were collected from 13 ponds in June 2006. Significant differences in concentrations of mercury were detected among taxonomic groups, with the omnivore Hydrophilidae and the predator Notonectidae containing lowest and highest concentrations of mercury, respectively. We also detected significant differences in concentrations of mercury in macroinvertebrates among ponds. Concentrations of mercury of some macroinvertebrates were above recommended thresholds for consumption by birds. Our study suggests that fishless ponds can produce large populations of mercury-contaminated macroinvertebrates that could be harmful to aquatic and terrestrial consumers.