The frequency and diversity of serious fungal infections is increasing [ 1 x 1 Nucci, M, Garnica, M, Gloria, AB et al. Invasive fungal diseases in haematopoietic cell transplant recipients and in patients with acute myeloid leukaemia or myelodysplasia in Brazil. Clin Microbiol Infect. 2013; 19: 745–751 Abstract | Full Text | Full Text PDF | PubMed | Scopus (43) | Google Scholar See all References , 2 x 2 Nucci, M and Anaissie, E. Fusarium infections in immunocompromised patients. Clin Microbiol Rev. 2007; 20: 695–704 Crossref | PubMed | Scopus (413) | Google Scholar See all References , 3 x 3 Nucci, M and Anaissie, E. Emerging fungi. Infect Dis Clin North Am. 2006; 20: 563–579 Abstract | Full Text | Full Text PDF | PubMed | Scopus (0) | Google Scholar See all References ]. Severely immunocompromised patients are particularly vulnerable to infection from unusual moulds and yeasts, which are present in the environment. Clinical manifestations range from colonization to chronic localized lesions to acute invasive and/or disseminated diseases. Localized infections may occur following penetrating trauma in healthy individuals; dissemination usually occurs among immunocompromised patients and the outcome is closely related to the degree and persistence of immunosuppression [ 4 x 4 Nucci, M, Anaissie, EJ, Queiroz-Telles, F et al. Outcome predictors of 84 patients with hematologic malignancies and Fusarium infection. Cancer. 2003; 98: 315–319 Crossref | PubMed | Scopus (163) | Google Scholar See all References 4 ]. Diagnosis usually requires isolation and identification of the infecting pathogen; however, serology, imaging techniques and clinical manifestations are not specific, and pan-fungal and species-specific PCR are useful investigational tools. Many of the emerging opportunistic moulds demonstrate in vitro and in vivo resistance to various antifungals. As a result, successful treatment may require adjunctive surgical debridement and, when possible, reconstitution of the host immune system.