Health-care workers are at risk to acquire HIV through occupational exposure to blood of HIV-infected patients. The mean risk after a percutaneous exposure is approximately 0.3%. A large inoculum and a source patient with a high plasma viral load increases the transmission risk. To ensure the safety of the operating team, we try to reduce HIV viral load in plasma prior to high-risk interventions (cardiothoracic and orthopaedic surgery). However, in 15.7% of the exposures occurring in the operating room, the possible source material is bone marrow. To make more accurate exposure risk assessments, we measured HIV-1 RNA in both plasma and bone marrow of five HIV-infected patients undergoing surgery. We found that the plasma viral load was not different from the viral load in bone marrow.