Introduction: The alogenic bone marrow transplant induces a major risk of sinus complications due to the need of a greater immunosuppression and total irradiation to avoid reaction, what promotes longer periods of leucopenia. Objective: To evaluate the importance of a prophylactic treatment protocol in leucopenic patients with chronic bacterial or non invasive rhinossinusitis who will undergo bone marrow transplantation. Methods: We evaluated 52 leucopenic patients with indication of a bone marrow transplant in Hospital Beneficência Portuguesa with the hematologic team from December 1996 to April 2000. They had risk of developing invasive fungal rhinosinusitis. Results: Seven (13,4%) developed the disease, and 3 (42,8%) resulted in causalities. According to our statistics, the incidence of invasive fungal rhinosinusitis (13,4%) is higher than reported in literature. Nevertheless, a lower mortality was observed (42,8%). Conclusions: This reduction may be due to an early diagnosis and to a prophylactic treatment of both fungal and bacterial chronic rhinosinusitis previous in these patients.