Bone marrow abnormalities are frequently observed in individuals with AIDS. Dysplasia, the most common abnormality, is found in more than 50% of patients infected with the HIV. The aim of this study was to assess trabecular thickness and collagen content as well as cellularity in the bone marrow of patients with AIDS. Sixty bone marrow samples were collected from the sternum of autopsied patients with or without AIDS (n = 30, each). Cellularity and trabecular thickness was assessed by performing hematoxylin-eosin staining; picrosirius staining was used to evaluate collagen content. Morphometric analyses were performed by using a Zeiss KS300 system (Kontron-Zeiss). Patients with AIDS showed a significant reduction in trabecular bone thickness and an increase in collagen deposition. No statistically significant differences were observed in cellularity between the 2 groups. Therefore, reduced thickness and increased collagen deposition were observed in the trabeculae of the bone marrow of patients with AIDS due to possible interaction between cytokines and bone marrow components.