Woven three-axial fabrics are generally produced in either three-dimensional or flattened modes. In case of the three-dimensional woven fabrics, the yarns in addition to the x and y directions are also laid in z direction. Flat woven fabrics have a third group of yarns in addition to direction of warp and weft yarns. Four ply 20 tex polyester/viscose (60/40 ratio) were used to weave the plain woven sample. The warp and weft densities of samples were 18 and 15 per centimeter respectively. In total eight woven samples in four categories were woven. One sample was a conventional woven fabric without the third yarn. One sample contained the third yarn placed at 45 degrees relative to warp and weft yarns. Four samples also contained the third yarns place in zig-zag strips with various widths in warp direction. Two samples contained the third yarn a move in weft directional and after that move in warp directional with different movement in warp directional. The samples were woven on a modified of conventional flat weaving machines. The effect of the third group of yarns in the woven three-axial flat fabric samples was investigated experimentally. Tensile properties of samples were determined along warp and the bias directions using Zwick tensile tester. The two sets of tensile results were compared and were found to be compatible. It was found that sample containing the third yarn along the warp exhibit a higher shear modulus than the reference sample. It was also found that in general the placement of the third yarn in the strips tends to increase the tensile strength of the four samples in comparison to the reference sample. However, it was found sample containing 1 cm zig-zag strip in comparison to 0.5, 2.0 cm strips have the highest tensile strength. Movement yarn in warp direction has not effect on tensile strength. It was concluded that the addition of the third yarn most positively enhances tensile properties of the conventional woven fabric at no extra costs.