Fifty-six-year-old Dan Krieg is the fifth known UPMC patient with a fungal infection to die since 2014 amid a federal investigation into mold cases at the health system's facilities.
The Pittsburgh Tribune-Review reports Krieg died Saturday at UPMC Montefiore.
Krieg had a successful kidney transplant in July 2015, but returned to the hospital in March.
A UPMC spokeswoman says Krieg's death was not directly related to the fungal infection but was caused by pneumonia.
Krieg's attorneys contend the mold led to his death.
A report by CBS Pittsburgh station KDKA last October said hundreds of tests for mold had been conducted on everything from bedsheets to bathrooms, ceiling tiles to food trays, and even dirt outside the building.
The federal Centers for Disease Control and Prevention says a specially ventilated room in the ICU might have been the source of the four earlier mold cases. The hospital suspended its transplant program Sept. 21 but resumed it about a week later after a review of procedures and treatments.