The UCU proclaimed the disparity in educational achievement for Glasgow and Edinburgh as "a tale of two cities".
Every Edinburgh constituency was in the top third of constituencies when it came to measuring qualifications. In Glasgow, however, three constituencies - Glasgow North East, Glasgow East and Glasgow South West - came top, third and eighth respectively in the league for no qualifications.
UCU general secretary Sally Hunt said: "There is a clear GlasgowEdinburgh divide in Scotland - one city with education and the massive personal benefits it can bring and the other without."
The statistics were based on the 2010 annual population survey by the Office of National Statistics of working-age people (16-64).
Glasgow's education convener, Jean McFadden, stressed that the figures were not reporting on the number of current school leavers who had no qualifications and had been taken out of context. The statistics were a reflection, rather, of the historic situation in the city when far fewer people were entered for qualifications - vocational or academic.
Councillor McFadden added: "For a number of years, Glasgow has been leading the way in a range of alternative qualifications - and youngsters have been very successful in gaining vocational qualifications in partnership with Glasgow's colleges."
A spokeswoman for the council said Glasgow was working with the Scottish Government to find ways of giving greater prominence to young people's achievements outside the Scottish Qualifications Authority's (SQA) framework.
But she added that last year, only 6 per cent of school-leavers in Glasgow had no SQA qualifications - a reduction from 8.6 per cent three years ago - and that 90 per cent of S4 pupils in the North East constituency achieved five or more Standard grades. Overall, 84.3 per cent of school- leavers in Glasgow went on to a "positive destination", with increases in both higher education and training.
Meanwhile, Edinburgh's deputy council leader, Steve Cardowie, commented: "These new figures confirm what we, and the wide range of companies who choose to invest here, have long known - namely that Edinburgh has among the most qualified workforces in Europe."