In the present study, blends of styrene/maleic anhydride copolymer with polyglutarimide were studied using a variety of methods. The blends were found to be miscible over the entire composition range and showed positive deviations in glass transition temperature from the ideal (linear) behaviour. Fourier transform infra-red spectra of the blends showed the presence of significant interactions between the two polymers. These interactions were found to be possibly of a polar nature, involving the carbonyls of anhydride and imide rings respectively. Although the blends are miscible, synergism was not found for the mechanical properties of the prepared blends. The mechanical properties of the blends, however, showed additivity, as mechanical properties varied linearly with the composition.