Abstract: Lincomycin and Clindamycin are two new antibiotics studied successfully in China.In this paper, 35S-labelled products--35S-Lincomycin and 35S-Clindamycin were madeby biosynthetic and semichemical synthetic methods. They were subjected to trials in pharmacology studies. Owing to the fact that Lincomycin is a metabolite of strepto-myces when it is prepared by the fermentation method, the microbes will pick up (NH4)2SO4 from the fermentation culture as a nutriment. Hence Na235SO4 was added to the fermentation culture-medium via biosynthetic method to obtain 35S-Lincomycin. Then 35S-Clindamycin was prepared by semichemical synthetic method from 35S-Lincomycin.After the purification of the semiproduct, it was esterified by sulfinyl chloride and chlorinated by carbon tetrachloride solution of triphenyl phosphine and then hydrolyzed with sodium hydroxide, and extracted by dichloromethane. Finally, the product was obtained by acidification with hydrochloric acid? the specific activity of both 35S-Lincomycine and 35S-Clindamycin being 2.3-2.8 mCi/mM, the activity percentage of recovery from the initial to 35S-Lincomycine being 8%, the chemical yield from 35S-Lincomycine to Clindamycin being 70%. The Rf value of 35S-Linco-mycine checked very well with the single spot of biologically standard unlabelled Lincomycine.