The oral toxicity of barium metaborate monohydrate (Busan 11-Ml) to Reticulitermes flavipes (Kollar) was evaluated in no-choice assays by feeding termite workers for 15 and 30 days on filter papers treated with concentrations of 500–40,000 ppm (weight/weight). In the 15 day assay, 30,000 ppm resulted in 92 ± 17% termite mortality and a concomitant 86% reduction in paper consumption. Feeding for 30 days on 1,500 ppm resulted in 100% mortality. Reduced paper consumption was associated with termite mortality, and feeding on low concentrations did not differ from that on control papers. Concentrations ≥ 20,000 ppm provided protection from termite feeding, while concentrations ≤ 5,000 ppm may be applicable in developing baits for subterranean termite control.