Notre Dame High, a Catholic high school in Glasgow, has only allowed girls to attend since its foundation in 1897.
And it remains the only non-private single-sex school in the country.
But families from a sister primary school, which allows both boys and girls, are now planning to run a survey on letting boys into the secondary.
Parents who send their children to Notre Dame Primary are gathering opinion from across the school community with families from all feeder primaries and the secondary asked to make their views known.
Martin McElroy, councillor for the Glasgow Hillhead ward, said families he had spoken to felt the time was right to have a debate about the future of the school.
He said: “Notre Dame has a long and illustrious history in the west end, but having a conversation now about its future would give parents the opportunity to decide what is best for their children.
“While there are no proposals to change the criteria for entry at the moment, I would welcome the chance for parents to have their say in a formal consultation.”
A spokeswoman for Glasgow City Council said the process was at an early stage and stressed any future change would have to be widely supported across the school’s community.
Even if parents from Notre Dame Primary vote in favour of the secondary becoming coeducational there is still a strong interest in preserving its status from other groups, including parents from convervative faith communities.
The spokeswoman added: “We are aware that some parents from Notre Dame Primary would like to explore the possibility of Notre Dame High School becoming a co-educational secondary school.
“Any changes need a statutory consultation with everyone who has an interest being able to express their views.
“Our officers are always happy to engage with parents, but any changes would affect parents from a number of schools and the views of all must be considered.”
The survey has been organised after concern from families from the primary who have both sons and daughters that when their offspring reach secondary age they will be unable to have them educated together.
Currently, boys educated at Notre Dame Primary have the option of going on to Thomas Aquinas, in Scotstoun, or John Paul Academy, in Summerston.
If parents want to send their boys to the local non-denominational school - Hyndland Secondary - they must make a placing request.
Professor Stephen McKinney, from Glasgow University’s School of Education, said single-sex state education had largely disappeared in Scotland, but was still valued.
He said: “The school is a legacy from the past when many of the major schools in the city would have been single-sex, as was the case in other parts of Scotland, particularly with a Catholic heritage.
“Attitudes at that time were that is was more appropriate to teach pupils separately along gender lines.”
Mr McKinney said that, although attitudes had changed over time, there was still a demand for single-sex education from parents in both the state and private sectors.
He added: “It is a bit of an anomaly, but Notre Dame High still attracts pupils from across the city and is still providing something parents want.
“Research has shown that for some subjects, such as sciences, being in single-sex classes can be effective for girls because they are not seen as being male dominated.”
The last time there was a challenge to the status of Notre Dame, one of the best performing schools in the city, was in 1999 when a group of parents took legal advice on the issue.
The education committee suggested a consultation, but it was rejected by the full council.