A report of the species Fusarium proliferatum causing systemic infection in a child with acute lymphoblastic leukemia is presented, with a review of the clinical and laboratory features relating to outcome in disseminated fusarial infections. Thirteen cases of disseminated infection due to Fusarium species have been reported, all but one of which were fatal. Hematologic malignancy is the commonest underlying illness. The frequent occurrence of multiple skin lesions, orbitofacial involvement, and fungemia is in contrast to the otherwise similar disseminated aspergillosis or mucormycosis. Fungemia in disseminated fusariosis may reflect a capacity for invasion of intravascular catheters by Fusarium species. Fusarium isolates from disseminated infections are variably sensitive to amphotericin B, ketoconazole, and miconazole and uniformly resistant to 5-fluorocytosine. The correlation between antifungal susceptibility status and clinical outcome is poor, reflecting problems in susceptibility testing, marginally effective chemotherapy, and serious impairment of host defenses. Attention to early diagnosis and the care of indwelling prosthetic devices may enhance survival until more effective chemotherapy is available.