Large numbers of universities and colleges employ staff on zero hours contracts, revealing the "murky world" of casualisation in the sector, according to research.
A study by the Universities and Colleges Union (UCU) showed that some institutions had more than 1,000 employees on zero hours contracts, under which staff do not know if they have work from one week to the next.
Universities and colleges were twice as likely to use such contracts than other workplaces, the study showed.
Freedom of Information requests from the union showed that 61% of further education colleges in England, Wales and Northern Ireland and 53% of UK universities employ teaching staff on zero hours contracts.
Around half of universities had more than 200 staff on the contracts, while five had more than 1,000.
The study follows recent revelations that around a million workers in the UK could be on zero hours contracts, prompting calls from unions and Labour for Government action to tackle the issue.
Business Secretary Vince Cable has asked his department to undertake a review of zero hours contracts.
UCU president Simon Renton said: "Our findings shine a light on the murky world of casualisation in further and higher education. Their widespread use is the unacceptable underbelly of our colleges and universities.
"Employers cannot hide behind the excuse of flexibility. This flexibility is not a two-way street and, for far too many people, it is simply a case of exploitation. We are encouraged that both the Government and the opposition have said they will be looking at zero hour contracts, but neither side has yet said anything that will give the thousands of people subjected to these conditions much hope.
"The extent of the use of zero hour contracts is difficult to pin down, as various groups have found, but their prevalence in our universities and colleges leads to all sorts of uncertainty for staff. Without a guaranteed income, workers on zero hour contracts are unable to make financial or employment plans on a year-to-year, or even month-to-month basis."
Almost 350 colleges and universities were covered by the study.
The union will take part in a debate on zero hours on the opening day of the TUC conference in Bournemouth on Sunday.