Alumina nanofibers at 0.25wt%, 0.5wt%, 0.75wt%, and 1wt% concentration were used to modify unsaturated polyester resin. Additionally, vinyl silane treated alumina nanofibers were used at the same concentrations and were compared to pristine alumina nanofibers. The SEM images showed a variation in the surface morphology when alumina nanofibers and the BET measurement showed surface area increase from 111 m2/g to 122 m2/g when nanofibers were treated with silane agent. The dispersion of alumina nanofibers into the host unsaturated polyester resin was successfully achieved by three roll mill dispersion. The TEM images showed good dispersion of alumina nanofibers in polyester resin. Although pristine nanofibers showed greater agglomeration at 1wt% concentration, the effect of agglomeration was reduced in the 1wt% concentration. The weight loss measurements from TGA showed that the thermal stability of nanocomposites increased with addition of nanofibers and the lower onset degradation temperature can be tailored to improve by a maximum of 5.5% for silane treated nanofiber. Viscosity and contact angle which are key factors affecting the processability has seen to be positively altered by silane treatment. Additional tensile, flexural, and Izod impact properties were evaluated for the nine material systems and the properties were summarized.