Polychlorinated biphenyls (PCBs) are persistent environmental pollutants, and their harmful effects on humans and animals are a major concern. Although the mechanisms of PCB toxicity have been studied, and they are known to largely accumulate in adipose tissue and liver, no therapy for PCB exposure has been established. To develop excretion-enhancing methods or antidotes for PCBs, animal models reflecting actual PCB bioaccumulation should be used. To establish such a model, we administered four levels of [³H]-labeled PCB-126 (710.4 × 10⁴, 142.1 × 10⁴, 28.4 × 10⁴, and 5.7 × 10⁴ dpm) to mice and investigated their excretion and tissue distribution. Lindane was used as a readily excreted comparator. 28.4 × 10⁴ or 5.7 × 10⁴ dpm [³H]PCB-126 resulted in excretion and tissue-distribution levels that were close to the detection limit. Administration of the maximum dose of [³H]PCB-126 resulted in continual excretion in feces and urine over the 8-day experimental period. In the mouse administered 142.1 × 10⁴ dpm [³H]PCB-126, the fecal and urinary excretion were reduced to a constant low level by day 8 after exposure, suggesting that the distribution of [³H]PCB-126 into the tissues had almost been completed. Our results suggest that mice administered 142.1 × 10⁴ dpm [³H]PCB-126 could be suitable as a PCB-126 bioaccumulation model for research to facilitate methods to enhance PCBs excretion and to develop therapies for PCBs toxicity.