Cellulose is the renewable, biodegradable, and most abundant polymer resource synthesized in plants. It is estimated that 1010-1011 tonnes of biomass are synthesized and destroyed each year (Helbert et al., 1996). Cellulose is the polysaccharide constituent present in the cell walls of grasses, reeds, stems and woody vegetation. It consists of repeating linear units of β-1,4 glucose (McCann et al.,1990). Cellulose fibers are grouped in the form of microfibrils ranging in size from a few nanometers to a few micrometers in length depending on the cellulose source (Oksman et al., 2006). Microfibrils comprise crystalline regions of long thread-like bundles of molecules stabilized by inter- and intramolecular hydrogen bonds between hydroxyl and oxygen groups of adjacent molecules separated by randomly oriented amorphous regions (Wyssling, 1968). The amorphous regions of cellulose can be easily broken down by controlled chemical treatment to obtain monocrystalline cellulose. The cellulose microfibrils in the plant cell wall are surrounded and joined by a loose network of other polysaccharides such as hemicellulose which is less crystalline than cellulose. Hemicelluloses provide mechanical strength and toughness to the plant cell wall (Vincent, 2000). In addition to hemicelluloses, other non-cellulosic materials such as lignin and pectins (water-binding polysaccharides) are also present in the cell wall. To obtain pure cellulose microfibrils it is necessary to remove hemicelluloses, lignin and pectin from the cell wall. The isolation of cellulose nanofibres/microfibres from plant cell walls is possible through the use of numerous processes: mechanical process (Nakagaito, 2004), chemical process combined with mechanical methods (Di...... paper medium.. .... to grow again, but the growth of bamboo leaves is relatively much faster. Even after maturity, the leaves fall off the tree as biological waste. So the present study describes for the first time, according to our knowledge, the isolation of CNCs from the leaves of two different bamboo species, use of CNCs and AgNPs for the preparation of bionanocomposites and further characterization We isolated CNCs from the leaves of two different bamboo species by chemicals combined with mechanical methods and adopted an eco-friendly approach to prepare nanocomposites (CNCs/AgNPs) using in situ method Since different species sources differ in terms of tissue structure and function, further analysis of the characteristics of CNCs and bionanocomposites from both bamboo species for comparison. The bionanocomposites were tested for their antimicrobial activity.