This paper is concerned with the **1**3C-NMR spectroscopy which has proven to be a useful technique in the structural analysis of polymers. The simplicity of the **1H-decoupled spectra, the broad range of chemical shifts, and the direct observation of backbone nuclei all combine to make **1**3C-NMR more attractive as a tool for the determination of polymer structure details than **1H-NMR. In general, **1**3C spectra yield information on composition and distribution of monomer units within the copolymer. In this note, **1**3C-NMR is used to determine the monomer sequence distribution (MSD) of styrene-maleic anhydride (SMA) copolymers. Downfield region of proton-decoupled natural-abundance **1**3C-NMR spectra of three styrene-maleic anhydrid copolymers are presented and discussed in terms of the sequence distribution of triads styrene-maleic anhydride copolymers.
