Staff at Dundee and St Andrews universities embarked on an eight-day strike over pay and and conditions on Monday.
Dozens of staff formed a picket line outside the main entrance to Dundee University on Monday morning before staff from both institutions attended a rally at Dundee West Church on Perth Road.
There were also smaller picket lines set up in different parts of both campuses.
Postmen refused to cross the picket line at Dundee and so did not deliver any mail to the university.
The strike has been called by the University and College Union which wants to see a better deal on pay and pensions as well as action taken to address inequality.
UCU Scotland president Carlo Morelli, a lecturer at Dundee University, told the rally universities were being subjected to “marketisation” that puts an emphasis on expanding campuses “at the expense of student education”.
He added: “Higher education is reaching a crisis point and this strike is a significant indication of this.
“The system cannot carry on as it is.”
Dundee University rector Jim Spence also attended the rally, telling strikers they have his “fullest support”.
Mr Spence, a former law lecturer at Dundee College, said the university’s international reputation was down to its staff.
He added: “Dundee’s reputation has been hard won and universities have to start appreciating their staff and treating them fairer.”
He said he was concerned about the long-term impact on students if staff are underpaid and overworked.
Mr Spence also referred to the resignation of former Dundee University principal Professor Andrew Atherton.
He said: “What a start (to my time as rector): you guys are on strike and the principal has disappeared.”
Up to 43,000 members of the UCU at 60 UK institutions are taking part in walk-outs. The union has said will affect about a million students in the run-up to the Christmas break.
Strikers include lecturers, student support services staff, admissions tutors, librarians, technicians and administrators.
UCU general secretary Jo Grady said further industrial action could follow in the new year if agreements are not reached in the disputes.
University leaders have said they will try to lessen the impact of the action and insist they want to work with the union to reach an agreement.
UCU said there had been “strong shows of support” for strikes at the universities involved and this had “sent a clear message that staff would not settle for pay cuts, increased pension costs or deteriorating conditions”.
It said staff had reached “breaking point” over issues including workloads, real-terms cuts in pay, a 15% gender pay gap and changes to the Universities Superannuation Scheme (USS), which the union says will leave members paying in more and receiving less in retirement.
Carol Costello, a spokeswoman for the employers’ side, said: “We will do all we can to ensure the strike does not impact badly on students and staff.
“The action and claims of the UCU that employers are forcing them into this cannot go unchallenged.
“Employers are prepared to invest in our people, but unaffordable sums of money would have to be diverted from other budgets unless individual members make a fair contribution.”
The strikes will take place on five days this week, and again for three days from December 2.