Abstract: A new potent narcotic analgesic, N-1-(β-hydroxy β-phenylethyl)-3-methyl-4-piperidyl-N-phenylpropionamide (simply named as F-7302) was labelled by tritiumhalogen exchange and catalytic reduction of N-1-(p-bromo-benzoyl methyl)-3-methyl-4-piperidyl-N-phenylpropionamide with tritium gas, using PdO/BaSO₄ as catalyst, removal of labile tritium by treating with alcohol, and final purification with silica-gel paper chromatography. Methyl orange was employed for the quantitative determination of ³H F-7302. The specific radioactivity was 59 ci/mM, and the radiochemical purity was 98%.³H F-7302 binding experiments with opiate receptors of mouse brain showed a high affinity and specificity. The saturation concentration for the stereospecific binding of ³HF-7302 was 4.5×10^-9M. and the dissociation constant was 1.25×10^-9M.The retio of specific/nonspecific binding was 10～15.