Fusarium spp., have been recognized during the past decade to cause disseminated infection, particularly in granulocytopenic patients undergoing intensive antileukemic chemotherapy or bone marrow transplantation. The lung, sinuses, and skin are the primary portals of entry. The periungual regions of the toes notably may be a particularly important site of initial invasion. Invasive Fusarium infections produce a pattern similar to that of invasive aspergillosis. Fusarium infections in granulocytopenic patients are characterized by pulmonary infiltrates, cutaneous lesions, and sinusitis. This emerging fungal pathogen often responds only to high doses of Amphotericin B. Pseudallescheria boydii causes sinusitis, pneumonia, and dessiminated infections in immunocompromised hosts and mycetoma in immunocompetent patients. Pneumonia due to P. boydii is clinically indistinguishable from that due to Aspergillus spp. Infections due to P. boydii are frequently refractory to antifungal chemotherapy, including amphotericin B.