Liquid nitrogen (LN₂) injection was used to against the red imported fire ant (Solenopsis invicta Buren) by taking the advantage of rapid killing, no side effects from residuals, and non-dependence on weather conditions of this method. Red imported fire ants workers were placed in glass bottles and treated by sub-zero temperatures for either two or zero minutes after thermo-equilibrium to determine the lethal low temperature. Fire ant nests were then treated by LN₂ and the survival of the ants was monitored. Thus -15 °C was shown to cause 100% of mortality of workers at 24 hours post treatment. Large numbers of ant corpses, which included larvae, pupae and queens, were discovered in the nest after LN₂ treatment. In a field experiment, 10 nests were treated by LN₂, while 9 were left as controls. The number of active nests significantly decreased to just one nest at the 14th day post LN₂ application and none was considered to be functional at the 21st day. These results suggest that LN₂ freezing is capable of eliminating individual fire ant nests effectively, and that this treatment is useful for areas of high human activity and for agricultural and other areas that have a low tolerance to conventional pesticides.