In developing countries like Ethiopia where concrete is widely used there is a steadily increasing the cost of concrete. This made construction work very expensive, due to less availability of concrete ingredients. In recent years, the use of natural fibers is become increasingly common in the civil engineering sector, as a part of energy-efficient and sustainable trends. Several researches demonstrated good properties of sheep wool fibres which a basis for compressive strength, tensile strength and improve environmental issue. The paper was focus on investigation on effects of sheep wool usage as a concrete composite material in C-25 concrete. The investigation is very important because, at present, the knowledge and the application of sheep wool fibers in this sector are relatively limited in our country. So an attempt has been made to achieve improved strength results using sheep wool fiber in conventional concrete. Experiments were conducted on concrete cubes and beam of various percentages of sheep wool fiber such as 0, 0.5, 1, 1.5 and 2% by weight of cement were tested for their workability, compressive strength and flexural tensile strength. The sheep wool were collected from different sources and dipped into salt water for 2 days to make hair surface rough. The wool has been sun dried. The mix ratio for C-25 concrete specimen was done in accordance with ASTM 595 and ACI 544.1R-96. From the study workability of the mix was reduced as percentage of sheep increase. The optimum amount of sheep wool fiber to produce concrete was 1.5%. Using 1.5% of fiber increase concrete compressive strength, flexural strength and split tensile strength property. It can be concluded that using sheep wool fibered concrete were preferable particularly to improve flexural strength.