China is conducting its first survey of the number of homosexual carriers of HIV, the virus that can lead to Aids.
China is in the midst of an Aids explosion
A health centre in the north-eastern province of Heilongjiang has collected 1,300 questionnaires, according to the state-run Xinhua news agency.
The centre has teamed up with a website dedicated to Aids issues, because people willing to take part openly in a survey on the subject are hard to find.
The survey is part of a US-Chinese Aids prevention programme launched in April.
The survey is aimed at determining the proportion of homosexuals and homosexual HIV carriers in the population.
The data collected in Heilongjiang "will be an important reference to the prevention and control on Aids of the nation", a provincial health official told Xinhua.
Earlier this month, Chinese Prime Minister Wen Jiabao warned that HIV/Aids had spread from high risk groups to the general population.
He said the disease was taking hold in huge areas of the countryside, where most of China's people live.
The Chinese government estimates that about 840,000 people are HIV-positive in the country.
But earlier this month, a UN report said 10 million Chinese could be infected by 2010.