The health department records show that 244 of the city's 681 schools flunked inspections in the past year, WBBM-TV, Chicago, reported Tuesday.
The television station asked food safety expert Kantha Shelke to review the health inspection reports.
Shelke discovered Anton Dvorak Elementary School failed city health inspections six times, earning it the distinction of having the worst record.
Reasons listed for the school's failure ranged from no hot water in bathroom sinks to hundreds of rodent droppings in the food service area.
At Cameron Elementary School, health officials found mice droppings in the main kitchen.
Mice droppings on nacho chips were responsible for sickening several students at Hirsch Metro High School, cited just last year for a rodent problem.