1,3-Thiazolidine-4-ones have been known to possess anti-HIV and anti-HCV activity as they are, respectively, HIV-1 non-nucleoside reverse transcriptase inhibitors and HCV NS5B RNA-dependent RNA- polymerase inhibitors. Some novel 1-[2-(benzoylamino)-3-methylbutyryl]-4-alkyl/arylalkylthiosemicarbazides, 2-[2-(benzoylamino)-3-methylbutyrylhydrazono]-3-alkyl-/arylalkyl-5-nonsubstituted/methyl-1, 3-thiazolidinones, were synthesized and evaluated for their antiviral activity. Antiviral activity of the synthesized compounds were screened against various types of viruses ( Feline Corona Virus ( FIPV), Feline Herpes Virus, HSV- 1(KOS), HSV- 1(TK-KOS ACVr), HSV- 2(G), Vaccinia virus, Vesicular stomatitis virus, Varicella-ZosterVirus TK+VZV, Varicella-ZosterVirus TK-VZV, Cytomegalovirus, Respiratory syncytial virus, Coxsackie B4 virus, Parainfluenza-3 virus, Reovirus-1, Sindbis virus and Punta Toro virus) in CRFK, HEL, HeLa and Vero cell cultures. Anti-HIV and cytotoxicity data were also obtained with the compounds using the strains HIV-1 (IIIB) and HIV-2 ( ROD) in an MT-4/MTT based assay. None of the tested compounds showed antiviral activity at subtoxic concentrations. For all the synthesized compounds anti-HCV NS5B RdRp activity was not observed at the concentration of 100 mu M which was the highest concentration tested.