By Sarah Rainsford
BBC News, Istanbul
A new constitution is being prepared to replace the current one, introduced after the military coup of 1980.
The document describes women as a vulnerable group needing protection.
The proposed constitution has already sparked fierce debate with a clause to allow women to attend university wearing the Islamic headscarf.
Speaking on Tuesday, Prime Minister Recep Tayyip Erdogan assured critics the new draft constitution will reflect the values and needs of all groups of society.
More than 80 women's groups have come together to voice strong opposition to the draft constitution, calling it a major step backwards for equal rights.
The current constitution in Turkey obliges the government to ensure equality for all - a clause that women's groups fought hard to include.
The new draft removes that, describing women instead as a vulnerable group in need of special protection.
Women's rights activist Selen Lermioglu calls that worrying proof that Turkey is still a highly patriarchal society.
"If the government accepts this it will show their ideology and mindset about women and men - that women are a group that needs to be protected," she said.
"If all laws and the whole constitution is prepared with this mindset, it can have a really bad impact," she added.
The group says it has not formed a common position yet on the issue of the Islamic headscarf, worn by more than 60% of Turkish woman but banned in state offices, schools and universities.
The government wants to change the constitution to ensure girls who cover their heads can attend university.
Women's activists, like the wider society here, are divided on that.
So far the new constitution has been drafted behind closed doors: now women's groups are demanding to be consulted.
They want to make this process an opportunity to push for more rights, not fewer, including a clause insisting on a temporary quota for women, to eliminate discrimination in all areas.
They argue that is the only way to lift Turkey from close to the bottom of the list in Europe on gender equality.