Abstract: zt-1 is a petential drug for treatment of Alzheimer's disease. For the study of this drug, isotope labeled compounds should be prepared. After reduction of 5-chloro-o-vanillin with sodium boron deuteride and triterid, and condensation, zt-1 labeled with tritium and deuterium are prepared. UV absorption spectrum and Rf of tritium labeled zt-1 are the same as authentic sample. The radiochemical purity of 3H-zt-l is more than 95%, and the specific radioactivity is 401. 3 GBq/g.