Using internet search engine Google can help doctors diagnose tricky cases, researchers have said.
The doctors favour using the internet search engine
A team of Australian doctors Googled the symptoms of 26 cases for a study in the New England Journal of Medicine.
In 15 cases, the web search came up with the right diagnosis, the paper published on the British Medical Journal website reports.
The authors say Google can be a "useful aid", but UK experts said the internet was "no replacement" for doctors.
Google is the most popular search engine on the web, with access to more than three billion medical articles - and searching for health information is one of the most common uses of the web.
And while doctors carry a huge amount of medical information in their heads, they may need to seek further help if they come up against an unusual case.
In each of the 26 cases studied, researchers based at the Princess Alexandra Hospital in Brisbane selected three to five search terms from each case and did a Google search without knowing the correct diagnoses.
They then recorded the three diagnoses that were ranked most prominently and selected the one which seemed most relevant to the signs.
The doctors then compared the results with the correct diagnoses as published in the journal.
Google searches found the correct diagnosis in just over half of the cases.
These included (CJD) Creutzfeldt-Jakob disease, the hormonal condition Cushing's syndrome and the auto-immune disorder Churg-Strauss syndrome.
The team led by Dr Hangwi Tang, a respiratory and sleep physician, said Google could be a "useful aid" diagnosing for conditions with unique symptoms and signs that can easily be used as search terms.
But they said a successful search needed a "human expert" user, and therefore patients would have less success trying to diagnose themselves on the internet.
They added: "Computers connected to the internet are now ubiquitous in outpatient clinics and hospital wards.
"Useful information on even the rarest medical syndromes can now be found and digested within a matter of minutes.
"Our study suggests that in difficult diagnostic cases, it is often useful to google for a diagnosis.
"Web-based search engines such as Google are becoming the latest tools in clinical medicine, and doctors in training need to become proficient in their use."
But Professor Mayur Lakhani, chairman of the Royal College of General Practitioners, said: "The internet is in no way a replacement for doctors - their clinical judgement and expertise will always be necessary to make sense of the information.
"Rather, it should be seen as a way of supporting doctors and their patients."
A spokeswoman for the Patients Association said: "Doctors have a very wide knowledge when it comes to diagnosing conditions.
"But we would be concerned if they were using websites to diagnose people, what would happen if they gave the patient the wrong information?
"Also, a lot of sites are not credible. There are lots of good sites out there, but we also know that there are many that are not credible."