Operations were cancelled after a rat was seen in a corridor at University Hospital in Coventry.
The day surgery unit was temporarily closed on Friday.
A pest control team were called in to deal with the problem over the weekend.
A spokesman for UHCW said: “The day surgery unit at University Hospital in Coventry was temporarily closed as a precautionary measure on Friday November 14 after a rat was seen in a corridor at 7am before any surgery had taken place.
“A pest control team were called in and have worked over the weekend to resolve the problem.
“The problem is contained and the day surgery unit, which performs minor surgical procedures, has now been reopened and services are being delivered normally.
“We can confirm that rat droppings were not found in any of the theatres and catering has not been affected although we have been working with environmental health as a precaution.
“This affected less than 30 patients and we would like to apologise unreservedly to them for being affected by this incredibly rare incident.”