Abstracts-Piperidine is one of pharmacologically active biogenic amines While two pathways for piperidine production have been reported, little is known about me tabolism of the compound.In the present study, piperidine and its hydroxylated, conjugated and unknown metabolites were detected in rat urine by radiochromato graphic analysis. Using GC-MS technique, it was confirmed that 3-hydroxypiperidine and 4-hydroxypiperidine are major metabolites of piperidine of either exogenous or endogenous origin. The findings substantiate the existence of a mechanism which inactivates piperidine in the living body, since both metabolites lack the potent phar macological activities as those induced by piperidine.