Almost half of those who took part in an independent survey for the festival worked more than 49 hours per week.
More than a third said they were on a zero hours contract and around a quarter said their fee for working at the festival was less than £1000.
The findings have emerged in the first independent survey of Fringe workers, which was carried out in the wake of last year’s festival.
More than 490 Fringe workers involved in 60 different venues and organisations took part in the survey. It found that just 54 per cent of staff had an employment contract and 30 per cent were hired as volunteers. A further 16 per cent were treated as freelance or self-employed, but not “pay rolled or taxed.”
The online survey was instigated in the autumn by the Edinburgh Festival Fringe Society after a campaign was launched last summer to ensure a fair pay deal for workers at the event amid claims of “widespread exploitation.”
The governing body has been urged to introduce a new code of practice for venues and promoters booking space for shows in its official programme. The Fair Fringe campaign wants all venue workers to paid the official Living Wage of £8.45 an hour and are also demanding a ban on zero hours conttracts and unpaid “trial” shifts.
Fringe chief executive Shona McCarthy, chief executive of the Fringe Society, said: “It is encouraging to hear that 90 per cent of respondents would choose to work at the Fringe again, and that 83 per cent were satisfied or very satisfied with their overall Fringe experience.
“We are mindful, though, that work still needs to be done to ensure everyone’s experience is as positive as it can be. Over the next few months we will be working closely with participants, venues and the city council to address areas for improvement identified by the survey, from pay and contracts to working conditions and staff welfare. We will look to have a number of measures in place before the 2018 Fringe.”
A spokesman for Fair Fringe campaign said: “Many of the concerns we had from our members at the Fringe have been corroborated by the results of this survey namely the number of people on zero hours contracts compared to the number of people who worked more than 49 hours.
“Our message to Fringe employers would be that if they know they are going to require staff for full-time hours then they should contract them for full-time hours or at least on a minimum hour contract thus ensuring that they receive related benefits such as accrued holiday entitlement.”