invasive aspergillosis (ia) currently is an important cause of mortality in subjects undergoing hematopoietic stem cell transplants (hsct) and is also an important cause of opportunistic respiratory and disseminated infections in other types of immunocompromised patients. we examined the medical records of 24 cases of proven and probable invasive aspergillosis (ia) at the hospital de clinicas of the federal university of parana, brazil, from january 1996 to october 2006. during this period occurred a mean of 2.2 cases per year or 3.0 cases per 100 hstc transplants. there was a significant relationship between structural changes in the bone marrow transplant (bmt) unit and the occurrence of ia cases (p=0.034, relative risk (rr) = 2.47). approximately 83% of the patients died due to invasive fungal infection within 60 days of follow up. some factors tended to be associated with mortality, but these associations were not significant. these included corticosteroid use, neutropenia (<100 cells/mm3) at diagnosis, patients that needed to change antifungal therapy because of toxicity of the initial first-line regimen and disseminated disease. these factors should be monitored in bmt units to help prevent ia. physicians should be aware of the risk factors for developing invasive fungal infections and try to reduce or eliminate them. however, once this invasive disease begins, appropriate diagnostic and treatment measures must be implemented as soon as possible in order to prevent the high mortality rates associated with this condition.