Stress has become an increasingly important occupational health matter in Japan. We found that noise exposure, 6kHz wave and its higher harmonics at the sound pressure level of 112dB, induced typical audiogenic seizures in the MRL/l mouse strain. The seizures are often fatal. Wild running preludes to seizures. Inhibition of wild running by restricting animal's activities successfully prevented the seizures, suggesting that an excessive physical load is a necessary step. The present finding indicates that MRL/l mice may be a useful model for human sudden deaths after excessive work loads.