Jute fiber (hessian cloth)-reinforced unsaturated polyester matrix composites (50 wt% fiber) were fabricated by hand lay-up technique. Tensile strength (TS), tensile modulus (TM), bending strength (BS), bending modulus (BM), elongation at break (Eb%), and impact strength (IS) of the composites were found to be 42 MPa, 2.7 GPa, 36 MPa, 2.1 GPa, 3%, and 21 kJ/m2, respectively. On the other hand, TS, TM, BS, BM, and Eb% of E-glass mat reinforced unsaturated polyester resin (UPR) composite were found to be 70 MPa, 3.8 GPa, 80 MPa, 2.5 GPa, and 5%, respectively. Then E-glass/UPR based composites (50 wt% fiber) were fabricated and the mechanical properties were compared with those of the Jute/UPR based composites. It was observed that E-glass fiber-based composites showed almost double mechanical properties as compared to jute composites. The interfacial shear strength of the jute and E-glass fiber-based systems was investigated and found to be 21 kJ/m2 and 21.56 kJ/m2, respectively, measured using the single-fiber fragmentation test. After flexural testing, fracture sides of both types of the composites were studied by scanning electron microscope (SEM) and the results showed that poor fiber-matrix adhesion for Jute/UPR based composites when it compared to that of the E-glass fiber composites. However, it was found that the E-glass fiber based composite has better strength as compared to jute fiber composite.