After the extensive flooding in New Orleans following Hurricanes Katrina and Rita, thousands of homes in the flooded areas had significant growth of mold. The potential health effects from exposures to these extraordinary environments are unknown. In February 2006, we investigated a cluster of patients with clinical specimens yielding Syncephalastrum, a zygomycete that rarely causes infection. We identified the cases of eight patients from September 12, 2005, to January 12, 2006, with specimens from sputum, bronchoalveolar lavage, endotracheal aspirate, ear swab, and nasal swab. All patients appeared to be transiently colonized without evidence of infection, even among immunosuppressed patients. Only one patient reported significant exposure to mold (working on mold remediation without wearing a respirator) on the day of his incident culture.