Confidential medical records revealing details of named patients' conditions at two Birmingham hospitals have been found dumped in a city street.
A doctor discovered the records of female patients from Birmingham Women's Hospital and kidney patients from the Queen Elizabeth Hospital.
Dr Alex Evans, who found the private documents near his home in Harborne, said: "These could have ended up in anyone's hands. You don't know what could have happened. It is a real breach of security."
A health watchdog boss warned that the patients involved could sue. Mark Olley, chairman of the East Birmingham Patients Forum, said: "Accidents may happen, but patients could pursue legal action against the hospitals because of the Data Protection Act."
Dr Evans, a diagnostic X-Ray doctor at Sandwell General Hospital, called for the hospitals to mount an immediate investigation.
Both hospitals are within walking distance of Metchley Lane, where Dr Evans found the patients' notes.
Records from the Women's Hospital contained detailed observations of named female patients.
Notes from the Queen Elizabeth Hospital detailed the condition of seven different patients.
Dr Evans, a doctor for 39 years, said: "Some hospital guidelines state that you are not meant to take any records off the premises.
"Both hospitals need to emphasise to their staff the importance of confidentiality.
"I am a medical practitioner and this is clearly a breach of patient confidentiality. Patients would expect their details to be kept private.
"There are times when patients do not even want their relatives to know about them."
He said he was returning the documents to both hospitals.
Phil Elliott, acting chief executive of Birmingham Women's Healthcare NHS Trust, said: "The trust takes any breaches of patient confidentiality very seriously and is obviously concerned to hear that information of this nature has been found outside hospital premises.
"We will be carrying out a full investigation and the appropriate steps will be taken to ensure this does not happen again."
A spokeswoman for University Hospital Birmingham Trust, which runs the Queen Elizabeth Hospital, said: "We are obviously concerned.
"This is the first time it has come to our attention and as soon as we are able to see the notes we will respond accordingly."
In February, confidential files from a city sexual diseases clinic were discovered in a skip.
The Whittall Street Clinic had removed the files in a clean-up but documents highlighting patients' intimate details were found nearby.