Opportunistic fungal infections are associated with high morbidity and mortality rates among immunocompromised patients such as recipients of organ, bone marrow or stem cell transplants, as well as patients with HIV infections and those receiving chemotherapy for cancer. Effective treatment and prevention of such infections, which are most commonly caused by theAspergillusandCandidaspecies, is therefore of increasing importance. A study presented recently at the 42nd Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) [San Diego; September 2002] showed that the cell wall synthesis inhibitor micafungin [FK 463; 'Funguard'] was superior to fluconazole ['Diflucan'] in preventing invasive fungal infections in patients receiving haematopoetic stem cell transplants (HSCT). The treatment success rate was significantly higher, in micafungin, compared with fluconazole, recipients; furthermore, the requirement for empirical antifungal treatment was significantly lower in patients treated with micafungin.