Biocomposites from carbon fibre (CF) and poly(hydroxybutyrate-co- hydroxyvalerate) (PHBV) bioplastic were fabricated by extrusion followed by injection moulding. The effects of fibre length and fibre loading on the performance of PHBV/CF composites were investigated. The amount of CF (for both 150 μm and 6 mm length) was varied from 10 to 40 wt.-%. The significant improvement in tensile strength (65%) and flexural strength (96%) was observed at 30 wt.-% CF (6 mm length) loading. The heat deflection temperature (HDT) of the PHBV/CF composites increased by 32% compared to neat PHBV. The fibre-matrix interaction was analysed using scanning electron microscopy (SEM). The tensile modulus of the composites was evaluated theoretically by the rule of mixture and the Hirsch model. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.