* * Fellow in Pediatric Hematology. Presently at

Physicians are becoming more aware of the existence and diversity of the infec-tious-mononucleosislike responses which patients may develop in certain circum-stances. Differentiation and identification call for knowledgable familiarity with these various clinical-hematologic responses. THIS review describes an assortment of f syndromes which mimic infectious mononu-cleosis {Ii~I) to a greater or lesser degree. Patients with any of these infectious mono-nucleosis syndromes (IMS) present sufficient clinical and laboratory findings to suggest the possibility of infectious mononucleosis, but the key points in making the differentiation, as we see it, are the pertinent history, some deviations from the typical I1~I pattern of expression, and above all no increase in heterophile antibodies after absorption of their serum with guinea-pig kidney antigen. The review first describes typical clinical and laboratory features of infectious mono-nucleosis to facilitate comparison with these simulating syndromes. Infectious Mononucleosi