Two children (ages 12 and 13 years) with transfusion-acquired human immunodeficiency virus (HIV) infection presented with facial pain and rhinorrhea. Radiographic imaging showed extensive paranasal sinus disease, presumed to be bacterial sinusitis, and the patients were treated with broad-spectrum oral antibiotics. Both patients were unresponsive to oral agents and were switched to intravenous antibiotics. Despite aggressive antimicrobial therapy, one patient (case 1) developed increased periorbital swelling and proptosis, and the other patient (case 2) developed symptoms of nasopharyngeal obstruction. Repeat imaging showed progression of the infiltrative process extending from the paranasal sinuses into the orbit (case 1), and nasopharynx (case 2). Surgical exploration and tissue biopsies were performed on both patients and the histopathology was consistent with Burkitt's/Burkitt's-like lymphoma. Combination systemic and intrathecal chemotherapy resulted in a complete remission in both patients. These reports illustrate the fact that Burkitt's/Burkitt's-like lymphoma in the paranasal sinuses may initially masquerade as an acute bacterial sinusitis. The ability of the tumor to extend rapidly from the sinuses into the orbit and nasopharynx reinforces the importance of early diagnosis and treatment. Burkitt's/Burkitt's-like lymphoma in the paranasal sinuses has not been previously described in HIV-infected children.