More than 300 pest infestations have been discovered at NHS Tayside sites since the beginning of the year.
Ants caused the most problems with 174 outbreaks, there were 39 incidents concerning mice, seven for flies, 24 for other insects, and six for rats.
The identity of the pests in a further 71 outbreaks has not been revealed.
The information was revealed after a freedom of information request. A patients group called for NHS bosses to control the problem or resign.
Margaret Watt from Scotland Patients Association said: "I am aghast, absolutely aghast.
"Patients are frightened to go into hospital as it is because of MRSA and C.diff and flesh eating bugs, this is only going to add to the stress and worry of our patients that have to go into hospital.
"I know if it was I, I'd be looking at every nook and cranny, looking under my bed just to make sure everything's clear."
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