Controversy and confusion in the classification of lymphoid neoplasia have long been sources of frustration as exemplifed by the statement of Rupert A. Willis in 1948, that "Nowhere in pathology has a chaos of names so clouded clear concept as in the subject of lymphoid tumors." Taxonomically, "Classifications are theories about the basis of natural order, not dull catalogues compiled only to avoid chaos." (Stephen J. Gould, 1989), but this definition can not always be applicable to the classifications of human diseases, even though they themselves are also biologic phenomena. The International Lymphoma Study Group has recently proposed "a revised European-American classification of lymphoid neoplasms", which has again resulted in the time of "the great debate". The major purpose of this article is, therefore, to assess the above classification.