The lawsuit, filed in Cook County Circuit Court Thursday, alleges the hotel is responsible for infecting Thomas Joseph Keane, 66, with the bacteria that causes Legionnaires' disease, the Chicago Tribune reported.
Keane dined at the Marriott July 27 and he apparently inhaled "dangerous aerosolized water vapor contaminated with Legionella bacteria."
He was later diagnosed with Legionnaires' disease and died Aug. 29, the lawsuit states.
Legionella bacteria was found in a decorative fountain in the main lobby of the hotel, where other visitors also were infected. The fountain has since been removed.
The lawsuit alleged the hotel failed to create and implement "appropriate control measures" to ensure the fountain was bacteria-free, and the hotel should have known and warned patrons of the contamination.
The hotel had no immediate comment.