Composite materials are extensively used in a wide range of applications. Natural-fiber-reinforced polymer matrix composites play a dominant role in the field of composites. The primary objective of this research was to investigate the effect of fiber size on the tensile properties of natural-fiber-reinforced polymer composites. The composite was fabricated by solution-casting technology using jute, coir and banana fibers, varying the fiber ratio as 3, 2 and 1% (weight/weight) and varying the fiber length as 10, 5 and 1 mm. Taguchi's design of experiments was followed to study the mechanical characteristics of samples by recording Young's modulus, modulus of resilience and yield stress through tensile tests. Analysis of variance was used to determine the effect of distinctive parameters on the tensile properties through main-effects plots, contour plots and regression equations. It was concluded from the results that the epoxy/jute sample showed good tensile characteristics followed by the epoxy/coir sample. The epoxy/jute sample, with 10 mm size and 3% fiber ratio, exhibited the highest Young's modulus of 3568 MPa. © 2019 ICE Publishing: All rights reserved.