Aspergillus infections have a very high mortality rate. Their incidence is growing because of the increasing number of immunocompromised patients. Treatment of Aspergillus infection is difficult, and the agents used have numerous adverse effects and toxicities. Recently, new and less nephrotoxic formulations of amphotericin B have come onto the market and other new drugs, such as voriconazole and terbinafine, are under evaluation for this infection. Restoration of host immune defences by tapering of immunosuppressive therapy in transplant patients or correction of granulocytopenia in haematological disease is the cornerstone of modern treatment of aspergillosis in immunocompromised patients. In patients with invasive aspergillosis it is very important to achieve therapeutic concentrations of antimycotic drugs as quickly as possible. Patients at high risk of developing aspergillosis (e.g. those with granulocytopenia) should be treated on the basis of clinical or radiological criteria alone if microbiological or histological diagnosis would significantly delay treatment. Conventional amphotericin B is still the first-line treatment for patients with invasive aspergillosis. In transplant patients receiving other nephrotoxic drugs, particularly cyclosporin, first-line therapy with one of the new amphotericin B formulations should be considered. If the emergence of renal toxicity in any patient precludes aggressive treatment, the patient should be switched to one of the new formulations of amphotericin B. For patients cured with amphotericin B, secondary prophylaxis is needed at the end of the intravenous therapy. Amphotericin B by aerosol or itraconazole are possible solutions. In non-invasive forms of aspergillosis, such as suppurative bronchitis, patients could be treated either with amphotericin B or itraconazole as first-line therapy.