By Michael Bristow
BBC News, Beijing
Liu Xiaojing is one of just a few well-known transsexuals in China
China is set to formalise the rules covering sex change operations to ensure that all those who want surgery meet certain requirements.
Those who apply for a sex change must be single, over 20 and have wanted the surgery for at least five years.
The proposed new guidelines, posted on the ministry of health's website, have been distributed for public discussion.
There could be hundreds of thousands of Chinese people wanting the surgery, news reports suggest.
The new rules aim to improve the oversight of sex change operations in China and ensure their safety, the ministry says.
It says those who want surgery must have openly lived and worked as a member of the opposite gender for at least two years.
They must have received psychological counselling for at least a year and have told their families about their wishes.
China's public security bureau must also agree to change the person's sex on their identify documents.
It was not initially clear whether or not the police would approve this change.
A spokesman from Beijing's public security bureau said he had not heard of the proposed regulations so could not comment.
Nearly 2,000 people are believed to have had a sex change in China, according to experts quoted by the state-run China Daily newspaper - and there could be up to 400,000 people considering having the surgery.
These proposed rules shows the government is becoming increasingly concerned about a group of people who are largely hidden in Chinese society, one expert told the newspaper.
Health professionals have until 10 July to comment on the proposals.