ABSTRACT There are needs and challenges in using natural resources to produce advanced materials with sustainability. So, in this modern time, natural fibres are used as reinforcement in composites because of their excellent properties, such as lower costs, biodegradability, lightweight, high corrosion resistance, high wear resistance, fewer health hazards and availability. However, greenhouse gases are released by the open burning of crop residues, such as wheat straw, rice straw, barley and many others, which increases global warming and declines air quality. So, in this experimental work, wheat straw fibres (WSFs) were used as natural fibres because of several factors, such as abundant availability, promoting of green composites and keeping rural areas clean (i.e. pollution-free) by reducing open burning. The same weight percentage of WSFs of different uniform mesh sizes was used with epoxy resin to fabricate the specimens for measuring the tensile and flexural properties as per the ASTM D 638 and D 790 standards. The results show that different behaviour of all specimens was observed under tensile and flexural loading. However, a specimen devoid of WSFs has the highest ultimate tensile and flexural strength, which were 25.064 MPa and 70.25 MPa, respectively.