The aim of the present study was to prepare and evaluate microspheres of Eudragit containing an antiviral drug stavudine. Microspheres were prepared by O/O solvent evaporation method using acetone/liquid paraffin system. The prepared microspheres were characterized for their micromeretic properties and entrapment efficiency; as well by Fourier transformed infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD) and scanning electron microscopy (SEM) which revealed the crystalline nature of drug in a final state. The in vitro studies revealed the controlled release of drug from microspheres up to 12 h and the best fit release kinetics was achieved with a Higuchi plot and found to be diffusion controlled. The yields of preparation and entrapment efficiencies were very high with a larger particle size for all the formulations. Mean particle size, entrapment efficiency and production yield were highly influenced by the type of polymer and polymer concentration.