The copolymerization of styrene (St) with maleic anhydride (MAh) under gamma radiation at room temperature inthe presence of benzyl dithiobenzoate (BDTB) was found to display "living" nature evidenced by constant concentration ofchain radicals during the copolymerization, linear evolution of molecular weights with conversion and narrow molecularweight distribution (Mw/Mn ＝ 1.23-1.35). The compositional analysis and the sequence structural information of thecopolymers obtained from DEPT (Distortionless Enhancement by Polarization Transfer) experiments demonstrate that thecopolymers obtained also possess strictly alternating structure.