The acquired immunodeficiency syndrome (AIDS) appears to be expanding both in the population at risk and in its clinical form of presentation. Persistent generalized lymphadenopathy has been reported in homosexual men who have immunologic abnormalities associated with AIDS. We are reporting ten cases of unexplained persistent generalized lymphadenopathy that have occurred in a heterogeneous population group at risk for AIDS (homosexual men, drug addicts, or Haitians). The morphologic findings of reactive follicular hyperplasia, increased interfollicular cellularity including an abundance of plasma cells and immunoblasts, preservation of the sinuses containing a sprinkling of polymorphonuclear leukocytes, and occasional multinucleated lymphoid cells constitute a constellation of features that are consistent enough so that AIDS should be included in the differential diagnosis.