U.K. doctors Hangwi Tang and Jennifer Hwee Kwoon Ng find that their patients often use the popular Google Internet search engine to try to diagnose their own illnesses.

They wondered if it works.

To test the strategy, they took advantage of a feature in The New England Journal of Medicine. Every week, the journal offers doctors the chance to hone their diagnostic skills by presenting a puzzling case history.

So Tang and Ng gave Google a chance to solve 26 of the puzzles.

The two doctors selected three to five search terms for each case history. They then typed them into Google and looked over the first five pages of search results for a diagnosis.

Google came up with the correct diagnosis 58% of the time, Tang and Ng report in the current online issue of BMJ, formerly the British Medical Journal.

"Our study suggests that in difficult diagnostic cases, it is often useful to 'google' for a diagnosis," the researchers conclude.

The catch: Tang and Ng are doctors, and their combined expertise was needed to choose the most likely search result.

"Patients doing a Google search may find the search less efficient and be less likely to reach the correct diagnosis," they note. "We believe that Google searches by a 'human expert', a doctor, have a better yield."