In the present study, blends of polyglutarimide (PGI) with styrene/maleic anhydride (SMA) copolymers showed complete miscibility with SMA containing 25, 33 and 50 mol.% maleic anhydride (MA), whereas blends with SMA containing 8 mol.% MA were found to be immiscible. These blends were studied using a variety of methods including thermal microscopy, FTIR and DSC. Positive T-g deviations from the ideal (linear) behaviour and changes in FTIR spectra of the blends indicate the presence of significant specific interactions between the two polymers. These interactions were found to be of a polar nature, involving the carbonyls of anhydride and imide rings, respectively. The intramolecular repulsion effect is possibly another factor contributing to enhanced miscibility.