Bis(β-alkoxycarbonylalkyl)tindichlorideswereinterfacialcondensedwithorganicdithio-alcoholstogiveaseriesofneworgano-tinpolymers.Experimentalparameterswerediscussed.Thepolymerssynthesizedweretestedfortheireffectontheheat-stabilizationofPVCresins.Theresultsareofinterestinthisareaofapplication.