This study presents a new approach to toughen Polyamide 6 (PA6) by using a low-molecular weight liquid natural rubber (LNR). The LNR is prepared by mastication of pale latex crepe in the presence of 0.5 phr Peptizol 7. The PA6/LNR blend samples are characterized in terms melt flow index, hardness, abrasion resistance, impact strength, flexural strength, tensile strength, and thermal properties. The impact strength of PA6 increases by about 67% upon addition of 10% LNR. The percolation model is applied to study of brittle to ductile transition. The percolation threshold for the brittle to ductile transition of the blend was found to be 14.5 wt % LNR, corresponding to the critical volume fraction of the stress volume, Vsc = 0.58, which is consistent with the calculated value of ≈ π/6. The PA6/LNR blends exhibit cavitation and matrix shear yielding, which would be the main contribution to the increases impact strength. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39750.