Laboratory bioassays were performed to characterize the acute contact toxicity of oxalic acid (OA) to Varroa destructor (Anderson & Trueman) and their honey bee hosts (Apis mellifera L.). Specifically, glass-vial residual bioassays were conducted to determine the lethal concentration of OA for V. destructor, and topical applications of OA in acetone were conducted to determine the lethal dose for honey bees. The results indicate that OA has a low acute toxicity to honey bees and a high acute toxicity to mites. The toxicity data will help guide scientists in delivering optimum dosages of OA to the parasite and its host, and will be useful in making treatment recommendations. The data will also facilitate future comparisons of toxicity if mite resistance to OA becomes evident.