From last few decades’ composite materials, ceramics and plastics has made a mark in the field of materials. Applications of these materials in engineering arespecially attributed to their low specific weight and comparatively high strength. Applications of composite materials vary from the basic daily needs to sophisticated luxury applications. The demand of natural fiber in the composite materials has been increased owing to low density, low cost and biodegradable properties of natural fiber.But at the same time the natural fibers has certain disadvantages viz. they are hydrophilic in nature due to which there is poor incompatibility of natural fiber with the matrix. This intensity of this disadvantage can be reduced with the help of chemical treatment of natural fibers. Natural fiber has tendency of water absorption, which can also be reduced with chemical treatment. There are number of factors which affect the properties of natural fiber reinforced composite viz. fabrication method, environment condition during fabrication, fiber and its quantity, matrix material. Any slight modification in the above said variables leads to change in the properties of the final composite material. In the present work, the tensile and flexural properties of natural fiber (abaca fiber) reinforced TPU composites have been investigated. The content of natural fiber in composites has been varied from 0 to 30 wt%. The reinforced fibers were chemically treated with NaOH followed by treatment with maleic anhydride in acetone, prior to fabricating of samples by injection moulding. It is observed that the composite containing 10 wt% of abaca fiber has highest tensile strength among all the composites fabricated for this study, whereas the tensile strength of pure TPU sample has maximum among all the samples fabricated during this research work.Maximum flexural strength is observed ofthe composite containing 30 wt% of abaca fiber.SEM examinations of the fractured surface reveal that primary failure mechanisms in composite as fiber fracture and fiber pull-out.