Chinese medicine purchased over the counter in Australia has been found to contain the DNA of endangered species.
Laboratory testing of the capsules purchased in 2012 found they contained DNA from snow leopard - and possibly tiger. Both species are listed on the Convention on the International Trade in Endangered Species. 
Roger Byard from Adelaide University's school of medicine said a research student purchased the traditional Chinese medicine from a shop at the Adelaide Central Market.
The traditional medicine known as Jian Bu Qiang Shen Wan, which is listed with the Therapeutic Goods Administration, is said to relieve arthritis pain. It is marketed as a herbal medicine.
"The listed ingredients are often quite different from what is in there," Professor Byard said, adding that about 13 per cent of Chinese traditional medicines contained animal species.
He said there was no evidence that snow leopard, native to the mountains of central and south Asia, had any effect on arthritis.
"You could eat a snow leopard from its nose to its tail and still have aching joints," he said.
There are less than 7000 snow leopards left in the wild, as few as 2500 of which are believed to be breeding.
The DNA was identified by chance during a toxicology study, in which Adelaide and Murdoch university researchers were looking at substitutions used in Chinese medicines.
Professor Byard said the discovery of snow leopard DNA was a shock and samples were re-tested several times to be certain.
He said the results also revealed ingredients derived from dogs, cats and rats. However these could have been present by accident, as a result of domestic animal contamination.
"Snow leopards, however, are so rare that we believe it had to be deliberately added."
The traces of tiger DNA were harder to confirm because the research team couldn't get enough proof on the readings.
Professor Byard said one of his major concerns was that the snow leopard DNA was discovered by accident as part of a small study. He said the study, led by DNA expert Mike Bunce from Murdoch University in Western Australia, would be expanded.
"Who knows what else is out there," Professor Byard said. "There is a dark side to traditional medicine that people don't want to recognise."
In an article published this month in the journal Forensic Science Medicine and Pathology, Professor Byard warned Chinese medicine was often overlooked as a driver of the illegal trade in endangered wildlife while more conspicuous trade in animal parts such as tusks and horns received more attention.
He said the effectiveness of many animal products in treating disease remained unestablished. Despite this, rhinoceros horn can sell for as much as US$50,000 a kilogram as it is believed to 'cure' everything from AIDS to cerebral haemorrhage, while monkey skeletons are used to treat general pain. Extracts from water turtle shells are used to treat cancer and the bile of moon bears is used for the treatment of digestive illnesses.