A new series compounds, α-methylene-β-carboxy-γ-thiobutyrolactones, have been prepared and their biological evaluation in vitro and in vivo have been described. The structures of these compounds were confirmed by 1H NMR and FAB-MS spectra. A new series compounds, α-methylene-β-carboxy-γ-thiobutyrolactones, have been prepared and their biological evaluation in vitro and in vivo have been described. The structures of these compounds were confirmed by 1H NMR and FAB-MS spectra.