Bacterial cellulose (BC) has established to be a remarkably versatile biomaterial and can be used in a wide variety of applied scientific endeavours, especially for medical devices. Nanocellulose, such as that produced by the bacteria Gluconacetobacter xylinus (bacterial cellulose, BC), is an emerging biomaterial with great potential in flexible radar absorbing materials, in scaffold for tissue regeneration, water treatment, and medical applications. Bacterial cellulose nanofibril bundles have excellent intrinsic properties due to their high crystallinity, which is higher than that generally recorded for macroscale natural fibers and is of the same order as the elastic modulus of glass fibers. Compared with cellulose from plants, BC also possesses higher water holding capacity, higher degree of polymerization (up to 8000), and a finer weblike network. In addition, BC is produced as a highly hydrated and relatively pure cellulose membrane, and therefore no chemical treatments are needed to remove lignin and hemicelluloses, as is the case for plant cellulose. Because of these characteristics, biomedical devices recently have gained a significant amount of attention because of an increased interest in tissue-engineered products for both wound care and the regeneration of damaged or diseased organs. Hydrophilic bacterial cellulose fibers of an average diameter of 50 nm are produced by the bacterium Acetobacter xylinum, using a fermentation process. The architecture of BC materials can be engineered over length scales ranging from nano to macro by controlling the biofabrication process. Moreover, the nanostructure and morphological similarities with collagen make BC attractive for cell immobilization and cell support. This review describes the fundamentals, purification, and morphological investigation of bacterial cellulose. Besides, microbial cellulose modification and how to increase the compatibility between cellulosic surfaces and a variety of plastic materials have been reported. Furthermore, provides deep knowledge of current and future applications of bacterial cellulose and their nanocomposites especially in the medical field.