This review summarizes the ongoing research activities on morphological changes being brought about by subjecting the natural cellulosic fibers to various chemical treatments. Most of the natural fibers being used as reinforcements in poly meric resins to form the polymer matrix composites are considered. The natural fibers contain an abundant number of polar hydroxyl groups and most of these hydroxyl groups are removed or modified in the cellulosic fibers when chemical treatments such as alkali, potassium permanganate, acetylation, benzoylation, acrylation, and silane treatments are carried out. A comprehensive review of mechanical characterization carried out on various combinations of natural fiber-polymer composites were presented. This review is expected to provide a ready reference for the researchers interested in the preparation of natural fiber reinforced polymer composites.