Piperidine is one of biogenic amines possessing nicotine-like synaptotropic actions on the nervous systems. Since piperidine produces multiplex physiological actions, a role for the amine as a modulator in neuroendocrine as well as neuronal functions has been supposed. In the present study, piperidine levels in the amphobian brains during activity and hibernation were examined by use of a mass fragmentographic technique and it was found that the brain piperidine concentrations significantly increased in the cold season especially during hibernation. The significance of the findings is discussed with respect to the hypnogenic effect of piperidine.