We present here the case of a patient inadvertently infused with intravenous fluid containing a "fungus ball." Because little is known about such cases, we surveyed 113 infectious diseases specialists for their experiences and ideas on management. Seventy-six responded, of whom 18 had seen a total of 24 cases. Intravenous-fluid containers were often defective, and the fungi involved were usually "contaminants." One patient developed significant fungal infection, and six others had transient symptoms temporally related to the infusion. Most specialists would administer antifungal therapy if symptoms developed, the patient was immunocompromised, or the fungus was pathogenic for humans.