Tannins are an important ingredient in the process of tanning leather that prevents decomposition and ususlaly imparts colour to the leather. Tannin is the fourth most abundant plant constituent after cellulose, hemicellulose and lignin. Tannins are water soluble poly-phenols with varying molecular weight depending on the bonds possessed with proteins and polysaccharides. Tannins occur commonly in the wastes fromforestry, plantmedicine, paper and leather industries. The treatment of this kind of tannin containing wastes, including adsorption, coagulation, liming, settling and biodegradation, is usually difficult because the nature of tannins are highly soluble in water and also it inhibit the growth of microorganisms in activated sludge. The objective of this present paper reviews the investigation about the biodegradability of tannin containing wastes with the help of biological treatment.