Abstract. Bola TS, Oluyege AO, Aina KS. 2020. Dimensional stability and tensile strength of biopolymer composite reinforced with hardwood fiber at varying proportions. Asian J For 4: 1-5. This study was designed to produce bio-composites made from three different wood species and at three different mixing ratio of plastic to wood on weight to weight basis. The main variables employed in this study are wood species of Triplochiton scleroxylon, Terminalia superba and Gmelina arborea; at plastic: wood of 40:60, 50:50, and 60:40 respectively. The composite samples were made through compounding and extrusion process. The properties evaluated were carried out in accordance with the American Standard Testing Methods of 570 and 790 to determine the dimensional stability and strength properties of the composites. The values obtained for the wood species range from 0.59 g/cm3 to 0.72 g/cm3, 0.59 % to 0.71 %, 0.63% to 0.7 %and 1.84 MPa to 2.07 MPa for density, water absorption, thickness swelling, and tensile strength respectively. Meanwhile, the values obtained from the mixing ratio range from 0.54 g/cm3 to 0.79 g/cm3, 0.53% to 0.79%, 0.42% to 1.00%, and 1.58 MPa to 2.37 MPa for density, water absorption, thickness swelling, and tensile strength respectively. It was observed that mixing ratio and wood species used in this study influenced the dimensional stability and strength properties of the WPCs. This study revealed that as the wood-flour content increased to plastic, the dimensional properties, and tensile strength values increases.