Manifestations of mantle cell lymphoma were recognized in the 1970s as distinct from those associated with the more readily classifiable lymphomas. It was not until the 1990s, however, that observation of a combination of immunologic, cytogenetic, and molecular genetic abnormalities characteristic of this new malignancy confirmed its existence. The clinical and pathologic entity was named mantle cell lymphoma and in 1994 was incorporated into the Revised European American Lymphoma Classification. Mantle cell lymphoma is a CD5 positive, B-cell lymphoma that usually displays the t(11;14). The lymphoma has a striking male predominance and is widely disseminated at diagnosis in 80% of patients. Mantle cell lymphoma responds poorly to available therapies, and the median survival is approximately 3 years.