Recently, the brown stink bug, Euschistus servus (Say), has become the dominant species in the stink bug complex on cotton, Gossypium hirsutum L., in Central Texas. Options to control the insect depend mostly on and are limited to the use of insecticide. Data are needed to determine the toxicity of currently available insecticides to brown stink bug and develop baseline mortality to assess resistance to insecticides in Central Texas. Using a glass-vial bioassay, the LC₁₀ and LC₅₀ values for selected commercially formulated insecticides, the technicalgrade active ingredients, and mixtures of active ingredients were determined for brown stink bugs captured in black-light traps near farmlands in Caldwell County, Texas. The LC₁₀ and LC₅₀ values showed the mixtures of technical-grade insecticides were 37- to 526- and 58- to 384-fold, respectively, more toxic to brown stink bug compared to the respective commercial formulations. The toxicological response of the technical-grade active ingredients relative to the mixtures varied from synergistic to antagonistic. Baseline data for brown stink bug mortality are useful for comparison with local populations should suspicion of tolerance to the insecticides develop in Central Texas. Data demonstrate lack of potentiation of the mixtures, probably because of absence of additivity or synergism in the composition of active and inert ingredients in the formulations or decreased composition of each component in the formulated mixtures.