We report on 44 cancer patients who had serious infections with unusual fungal pathogens and who were cared for at our cancer center between 1974 and 1986. Twelve different fungal species accounted for these infections, including Trichosporon beigelii, Fusarium species, Geotrichum candidum, Curvularia species, Drechslera species, Penicillium species (but not Penicillium marneffei, Rhodotorula rubra, Pseudallescheria boydii, Pichia farinosa, Torulopsis pintolopesii, Saccharomyces cerevisiae, and Cunninghamella bertholletiae. Skin lesions were noted in seven patients, and sinusitis occurred in four. Twentyfour patients had disseminated infection, 12had involvement of a single organ, and eight had fungemia alone. Features that correlated with a poor prognosis were persistent neutropenia and disseminated visceral infection but not fungemia alone. Wesuggest that unusual fungi have now emerged as significant pathogens in this patient population. Fungal sinusitis, previously caused by Aspergillus species and the phycomycetes, also occurs as a result of some of these newly recognized fungi. A high level of suspicion should be maintained when any of these unusual fungi are cultured from clinical specimens from immunocompromised patients.