A series of alpha-substituted-1,2,3-thiadiazoleacetamides were prepared and tested in vitro against tobacco mosaic virus. The preliminary bioassays indicated that some of the new compounds are good as compared to the commercial pesticide Virus A at 500 mg/L, and the activity was influenced by the nature of the substituents. 3D-QSAR models were established based on the antiviral activity of the compounds. It has also been found that some of the new compounds also exhibit significant anti-HBV activity in human hepatoblastoma-derived liver Hep-G2 cells.