The bone marrow findings in 5 older adults with infectious mononucleosis or mononucleosis‐like illnesses are presented. These individuals were initially considered to have lymphoproliferative disorders which often have similar constitutional signs and symptoms. All had atypical lymphocytosis of the peripheral blood. In addition, there were also abnormalities in the bone marrow. The most common findings included focal collections of lymphocytes and the presence of granulomas. The granulomas were small without caseous necrosis and giant cells were infrequent. This is in contrast to the idea that the bone marrow is normal in infectious monoculeosis and gives support to performing core biopsies as the aspirate smears in these individuals did not demonstrate the focal lymphocytosis or granulomas. Whereas, infectious mononucleosis and mononucleosis‐like illness may be uncommon in the older individual, they certainly are not rare and it is important to differentiate these benign disorders from the more serious lymphoproliferative diseases. Heterophil test and/or Epstein Barr titers are important confirmatory te