Background: The myelogram is the collection of elements provided by microscopic examination of a hematopoietic bone marrow smears collected by puncture-suction. It is considered one of the most valuable diagnostic tools for assessing hematological abnormalities. Methods: We conducted the present retrospective study of 305 patients collected over a 3 year period, from February 2015 through June 2018, performed in the hematology laboratory of the Avicenna military hospital in Marrakech to expose the main bone marrow indications, review its diagnostic contribution, evaluate the practice of the myelogram in our context, and propose recommendations to improve the practice of this examination. Results: The myelogram study allowed to make the diagnosis of 53 (17, 4%) megaloblastosis cases, fifty five (18%) cases of medullary plasmocytosis. Acute myeloblastic leukemia was found in 27 patients (8.8%) followed by chronic lymphocytic leukemia in 11 patients (3.6%), comes after chronic myeloid leukemia in 11 cases (4.3%), while acute lymphoblastic leukemia is in 16 cases (5.2%). The myelogram was normal in 60 cases (19.6%). It objectified a reactional marrow in 49 cases (16%). The myelogram was impossible to interpret in 21 cases (7%), in which the sample was diluted. Conclusion: This general review of haemopathies has highlighted the importance of the myelogram as an indispensable tool for diagnosis. In our study it was possible to know the contribution of this examination, which is linked to its good interpretation.