More than a third of children in some parts of England have not been allocated their first choice of secondary school for the autumn, according to a sample of councils.
Around half a million families are finding out which school they have been allocated on National Offer Day.
While for many the day will bring excitement, thousands of pupils are likely to miss out on a place at their first choice of school.
Last year there were 533,314 applications for a secondary school place and 84.2% of children across England were offered their preferred school.
Overall figures for this year will not be released by the Department for Education until June, but analysis of a sample of early figures from local councils suggests that one in 10 children could miss out on their first choice.
A wide fluctuation was evident, with virtually all 11-year-olds getting their first preferences in some areas, while more than a third missed out in others.
Out of 20 local education authorities that responded to the Press Association, three-quarters reported an increase in the number of applications received from last year.
Figures obtained through the survey of local councils show that:
: : Across 20 councils that responded, an average of 87.6% of applicants received their first preference.
: : In Birmingham, more than one third of children applying for a school missed out on their top choice. Out of 16,664 applications, 10,674 were offered their first preference - 64%.
: :Southend-on-Sea (79.1%), Trafford (80%) and Bolton (82%) also had relatively high numbers of applicants not getting into their top school.
:: In East Riding, 96.4% of children got their first choice. Only 0.8% did not get their first, second or third preference.
: : This was closely followed by Leicester County Council (95.5%) and Norfolk County Council (94.7%). In Sunderland City Council only 34 children - less than 1.3% - did not get their first, second or third choices.
The figures do not include data from the body managing the London borough councils.
Last year, around one in six children across England did not get a spot at their first choice.
Primary schools have been struggling to keep up with demand in recent years due to a rising population and this is now moving through into secondary schools.
The Government has said it pumped £5 billion into creating half a million new places over the last parliament and has committed a further £7 billion over the next six years.
Town hall bosses have warned that children could be left without school places if councils are not given more powers to deal with increasing demand.
The Local Government Association has issued a fresh call for authorities to be handed the ability to open new secondary schools, or force academies - which are not under council control - to expand, arguing that without these powers, councils will not be able to meet their legal duty to ensure every child has a school place.
Justine Roberts, chief executive of parenting website Mumsnet, said while many families are happy with the place their child is given, others are left feeling anxious and struggling to find a spot at the school they want for their youngster.
She said: "How well the school admissions system works depends almost entirely on where you live. Lots of parents are very content with the school places allocated to their children, but in some areas - parts of London, Bristol, East Sussex and Birmingham, for example - the admissions system is starting to feel seriously creaky.
"Stories abound of some families cheating the system, which only adds to people's anxiety and sense of injustice; many Mumsnet users say that their children can't get into schools that are a few hundred metres away from their front doors.
"Parents are struggling, and the consensus on Mumsnet is that more needs to be done by central and local government to address the problems now, rather than waiting for places to come online in a few years."
Families who do not win a place at their favoured school can appeal, and one admissions expert said more are now willing to take that step, and get legal help to do so.
Matt Richards, of legal advice firm schoolappeals.com, said: "A few years ago out of 10 phone calls to us, maybe two would pay for some help. Now it's more like 50%.
"People are much more switched on in terms of their legal rights and in terms of not wanting to do it on their own and asking for help."
Last year, there were 54,600 appeals against school allocations - 3.7% of the total number of admissions to state schools. Just over a fifth (22.8%) of the appeals actually heard by a panel were decided in favour of the parents.
Schools Minister Nick Gibb said: "We want every parent to be able to send their children to a good local school. Despite rising pupil numbers the vast majority of parents are able to do so.
"The Government is investing billions of pounds creating new schools and new school places and through our free schools programme we want to open 500 more new schools during the five years of this Parliament."