And in as many as one in four eateries, the situation is so bad that the restaurants are at risk of closure.
Sampling the local food is a highlight of most tourists' stays in the Italian capital, but the figures, which come from Italy's health police and were first reported on Monday in Il Corriere, are enough to put anyone off their pizza.
One osteria reportedly had such a serious infestation that cockroaches had made their way into the cash registers, while meals in a Japanese restaurant were found to contain rodent feces.
Overall, half of the restaurants examined were guilty of some form of "irregularity", a category which includes infestations along with other problems such as serving food past its use-by date, preserving perishable food incorrectly or storing cleaning products too close to foodstuffs.
Nas, the Italian health police, carried out checks on 727 restaurants, most of them situated in Rome's historic centre, between November 2015 and October this year. This was a particularly popular year with tourists to Rome, as over 18 million pilgrims visited the eternal city to celebrate the Catholic Jubilee year.
Criminal investigations have opened into 33 people, who may have violated laws regarding safety in the workplace, and a further 300 restaurant owners have been reported to the local health authorities, ASL.
A total of 521 fines, worth €658,000, were issued. Health police also seized large quantities of food; €20,000 worth of oil, 2,300kg of meat products and 2,300kg of fish.