Fungi are increasingly recognised as major pathogens in critically ill patients. Candida spp. and Cryptococcus spp. are the yeasts most frequently isolated in clinical practice. The most frequent filamentous fungi (moulds) isolated are Aspergillus spp., but Fusarium spp., Scedosporium spp., Penicillium spp., and Zygomycetes are increasingly seen. Several reasons have been proposed for the increase in invasive fungal infections, including the use of antineoplastic and immunosuppressive agents, broad-spectrum antibiotics, and prosthetic devices and grafts, and more aggressive surgery. Patients with burns, neutropenia, HIV infection and pancreatitis are also predisposed to fungal infection. The epidemiology and clinical features of fungal infections are reviewed, together with antifungal agents currently or soon to be available.