Three safety probes at Derriford Hospital
Three incidents, including one in which a needle was left in a patient, are being investigated by Derriford Hospital in Plymouth.
Two investigations concern the misplacement of naso-gastric tubes used for feeding and administering drugs.
All three incidents occurred after November according to a report passed to the hospital's board.
It said that the affected patients, none of whom were reported injured, had received an apology.
The incidents could be classified as "never events", so called because they should never have happened.
That will depend on a meeting between the hospital managers and the new Devon Clinical Commissioning Group.
Greg Dix, director of nursing for Plymouth Hospitals NHS Trust, said: "As reported in our public trust board papers, our last never event was on 20 March 2013.
"We have not had any further confirmed never events."
Medical Director Dr Phil Hughes said: "In healthcare a high incident reporting rate is often associated with a strong patient safety culture.
"This is exactly what we have developed at Plymouth Hospitals and it is important that we maintain that good, open reporting culture and learn from every incident to constantly improve patient safety.
"We put patient safety at the heart of everything we do.
"We perform 80,000 operations each year, some of them extremely complex and high risk.
"We want to reassure patients waiting to come in to be treated that the risk to them of something untoward happening is very, very small indeed.
"They can be reassured that we have a strong safety culture, because we learn from the rare occasions that things do go wrong."