In recent years, natural fiber reinforced composites have drawn much attention due to its cheap cost, biodegradable, flammable, nontoxic, and nonabrasive qualities. Natural fibers such as flax, bamboo, sisal, hemp, ramie, jute, and wood are especially captivating among the several types of natural fibers. Natural fibers have been extensively studied worldwide for their potential use as reinforcing materials in the production of diverse composite materials. The quality of the fiber-matrix interface is one of the most crucial variables that determines the ultimate performance of the composite materials. Natural fibers can be pretreated to improve surface roughness, chemically alter the surface, clean the fiber and halt the process of absorbing moisture. Among the various pretreatment techniques alkali treatment is one of the most affordable and cautious chemical techniques for the surface modification of natural fibers. Better mechanical interlocking is produced by alkaline treatment because it enhances surface roughness and removes the cellulosic substance that covers the external surface of the fiber cell wall. This article provides a review on the use of pretreated natural fibers in polymer matrix-based composites. The effect of surface modification on the mechanical properties of natural fiber reinforced polymer based composites has also been discussed in this review study.