Figure 3 presents the average stress–strain curves for the flax fiber reinforced thermoplastic composites having various fiber content (0, 5, 10, 15, and 20% w/w). It is clear that as the fiber content increases the strain at failure of the composite decreases from 17% to 6%. The drastic decrease was observed for the composite having 5% w/w of flax fibers (from 17% to 8%). When the fiber content increased further from 5% to 20% w/w a slight decrease was observed from 8% to 6%. This indicates that addition of fiber to the matrix decreases the ductile nature of the polymer. The values obtained for the stress at failure, strain at failure, and tensile moduli are given in the Table 1. It is found that when the fiber content increases from 0% to 20% w/w, stress at failure and tensile modulus increases from 3.2 MPa to 8.9 MPa and 125 MPa to 465 MPa, respectively. For the composite having 20% w/w fiber content, an increment of 272% occurred in tensile modulus while for that of the stress at failure is 178%. At 5% w/w fiber content, because of lower fiber content, the stress transfer will not occur properly. As the fiber content increases, because of good fiber dispersion, the stress transfer between fiber and matrix occurs properly, as a result the tensile strength and modulus increases.