Polylactide, PLA, is a biodegradable thermoplastic polyester derived from biomass that has restricted packaging applications due to its high brittleness and poor crystallisation behaviour. Here, new formulations based on natural rubber-PLA blends have been developed. The processing windows, temperature, time, and rotor rate, and the rubber content have been optimised in order to obtain a blend with useful properties. The rubber phase was uniformly dispersed in the continuous PLA matrix with a droplet size range from 1.1 to 2.0 μm. The ductility of PLA has been significantly improved by blending with natural rubber, NR. The elongation at break improved from 5% for neat PLA to 200% by adding 10 wt% NR. In addition, the incorporation of NR not only increased the crystallisation rate but also enhanced the crystallisation ability of PLA. These materials are, therefore, very promising for industrial applications. © 2011 Elsevier B.V. All rights reserved. The work was supported by the Spanish Ministry of Science and Innovation (MICINN) under project MAT 2007-61116. NB thanks the CSIC for a JAE-Pre grant. RV also acknowledges a Ramon y Cajal contract from MICINN Peer reviewed