The mechanical characteristics of cellulose fibres in biocomposites (epoxy resin/Musa textilis) were investigated relative to the microstructure of these fibres as determined by porosimetry and electron microscopy in terms of their utilization in composite systems. The influence of the chemical treatment via alkali (NaOH) on the change in surface properties and the interfacial interaction of fibres with an epoxy resin was investigated as well as mechanical characteristics of abaca/epoxy composites. The porosity of abaca fibres reached 57% on average, and the averaged tensile strength value was 641 MPa and a Young modulus of 26 MPa. Evaluated composite systems were prepared through a vacuum infusion in which various orientations of long ordered fibres in these composites were evaluated along with the influence of a 6% NaOH chemical treatment on the resultant mechanical properties. The alkali treatment increased the tensile strength of the observed composite systems by up to 16 MPa. The chemical treatment of the abaca fibres led to an increase in the interfacial interaction, which was evaluated with electron microscopy.