Abstract High-density biopolyethylene (HDBPE) used as a matrix in composites reinforced by curaua fibers (5, 10, 15 and 20 wt%, 1 cm) was obtained on an industrial scale by polymerization of ethylene derived from sugarcane ethanol. Castor (CO) and canola (CA) oils were used in the preparation of composites (5, 10, 15, and 20 wt%) as a potential compatibilizer of the polar fibers and nonpolar matrix to facilitate the respective processing and to intensify polymer and reinforcement material interface interactions. The composites were characterized by SEM, DSC, TGA, DMA, and flexural and impact strength measurements. The results indicated that the incorporation of oils in various compositions, particularly CO, generally led to improved properties compared to the HDBPE/fiber composite material, indicating the potential of the oil as a compatibilizer at the fiber/matrix interface.