Biodegradable, biocompatible polylactide (PLA) synthesized from renewable resources has attracted extensive interests over the past decades and holds great potential to replace many petroleum-derived plastics. With no loss of biodegradability and biocompatibility, we highly toughened PLA using a novel bioelastomer (BE)-synthesized from biomass dials and diacids. Although PLA and BE are immiscible, BE particles of similar to 1 mu m in diameter are uniformly dispersed in the matrix, and this indicates some compatibility between PLA and BE. BE significantly increased the cold crystallization ability of PLA, which was valuable for practical processing and performance. SEM micrographs of fracture surface showed a brittle-to-ductile transition owing to addition of BE. At 11.5 vol%, notched Izod impact strength improved from 2.4 to 10.3 kJ/m(2), 330% increment; the increase is superior to previous toughening effect by using petroleum-based tougheners. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.