Staff at five universities have started strike action as a dispute with employers over pay becomes “increasingly bitter”.
Mary Senior, of the University and College Union (UCU), said a quarter of Scotland’s universities would be affected by the action.
Union members are protesting at Stirling University on Monday June 20, Queen Margaret University in Edinburgh on Wednesday June 22 and Glasgow Caledonian University on Thursday June 23.
Protests will also be held at Edinburgh’s Heriot-Watt University and Glasgow School of Art on Friday June 24.
The dispute centres on the 1.1% pay rise offered to staff, which union leaders say comes after a real-terms pay cut of 14.5% in the last six years.
UCU leaders also say university principals have been receiving pay rises of up to 15%.
As well as taking strike action, university staff are also working to contract, meaning they will only work their fixed hours and refuse to take on any additional work or voluntary duties - with the UCU warning this could disrupt exam-marking over the summer.
Ms Senior said: “With over a quarter of Scottish universities being hit by strike action this week, and more planned for the weeks and months to come, this dispute is becoming deeper and increasingly bitter.
“The absolute last thing lecturers and university staff want to do is go on strike.
“Staff have been forced into taking action and the breadth of what it taking place shows that our members are resolute.
“The only people who can resolve this dispute now are the employers. They need to come back with a fair and reasonable offer.”
A spokesman for the University and Colleges Employers Association said: “UCU’s latest call on its members to take strike action to target their own individual HE (higher education) institutions including their open days is, of course, disappointing but it is important to note that few academic staff actually voted to support industrial action.
“HE institutions tell us that the majority of their staff understand the financial realities for their institutions and the need to showcase their courses and campuses effectively.
“Rather than ask their members to inflict damage on themselves, their colleagues, their students and potential students, as well as their HE institutions as a whole, we would like to see UCU conduct a consultation that enables their members to consider all the elements of the full, fair and final offer that is on the table.”