This work is dedicated to protein purification. When we talk of proteins someone has rightly said "never waste pure thoughts on an impure protein". Nothing makes sense unless we are rellay working on pure protein. This book will be useful to the beginners of protein purification. The book systemetically illustrates the points to partially purify the protein alpha D mannosidae from Tomatao (Lycopersicon esculentum). The crude tomato has been used to isolate alpha D mannosidae.The book typically explains the basic details right from crushing of the crude tomato in liquid nitrogen to ammonium sulphate precipitation and dialysis to remove the salt. The purification step used are ion exchane chromatography and gel filtration. Activity of the purified enzyme was checked by taking the substrate p-nitrophenyl ?-D mannopyranosidase.