In HIV infection, numerous alterations of the hematopoietic system, with frequent cytopenias in peripheral blood and dysplasia of the bone marrow, have been observed. In order to assess the incidence of the myelodysplastic anomalies, 69 bone marrow aspirate smears from 47 patients with group IV HIV infection, as classified by CDC, have been studied. Various degrees of myelodysplastic alterations were found in all cases; however, dysgranulopoiesis was more frequent and more accentuated than other kinds of dyshematopoiesis. Intense vacuolization, especially in the granuloblastic series, was very frequent. It is felt that a bone marrow configuration that is highly indicative of overt AIDS can be sketched. The human immune deficiency virus may be either directly or indirectly responsible for myelodysplastic alterations.