One hundred twenty-one bone marrow specimens, including 107 from hematologically normal patients, were examined histologically and the reticulin content quantitated utilizing a scoring system modified from that described by Kundel and associates.5 Reticulin content is correlated with patient age, sex, marrow cellularity, anatomic site, and method of obtaining the specimen. The overall normal range is considered to be 0 to 1+ in all aspirated material; however, the upper limit of normal should be extended to 2+ when the specimen is obtained by tissue biopsy technics. Scores of 3+ or 4+ are considered sclerotic in any situation, and such patterns occasionally are seen in the absence of apparent sclerosis as demonstrated by routine hematoxylin and eosin technics.