Jute fiber mat reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 32 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in the vacuum. Tension and three-point bending tests were carried out to evaluate the effect of fiber contents on these mechanical properties of above-mentioned composites. The results showed that as the fiber weight content increases, tensile strength and modulus increase and the improvement had occurred at 22 wt% of fiber weight content with respect to that of neat resin. As the fiber weight content increases, flexural strength and modulus increase and the improvement had occurred at 11 and 32 wt% fiber contents for the flexural modulus and strength respectively compared to those of neat resin. Fiber pull out mechanism is the failure mode revealed at the fracture surfaces under tensile loading as well as at tension side of composites under bending loading.