This is to review from the existing literatures the various methods of determination, problems involved in the determination of metabolizable energy(ME) values of poultry feedstuffs that is the most widely used energy term in poultry nutrition. An attempt will also be made to introduce the newly developed determination method of ME by Sibbald and his associates. It was found that conventional methods of ME measurements such as total collection method and indicator method require a great deal of labor and time. It should also be pointed out that these methods have some technical problems as well. Experimental evidences indicate that the ME content of feedstuffs may be affected by breed, age, substitution level of basal diet, kind of basal diet, methods of chemical analysis and chemical composition of experimental diet. Standard procedures and technical advantages of newly developed method of "True Metabolizable Energy" system are fully described.