Staff at York, Durham and Newcastle universities have started eight days of strike action today.
University and College Union (UCU) members are walking out in a dispute over pensions, pay and working conditions. University leaders say they want to co-operate to reach an agreement and will work to minimise disruption.
Striking staff were on picket lines at the entrances to their universities from 8 am, outside the King's Gate entrance in Newcastle and near the Palatine Centre in Durham.
Picketers plan to make their way to Old Eldon Square, in Newcastle, for a rally at 1 pm.
Up to 43,000 members of the University and College Union (UCU) at 60 UK universities across the country will walk out, disrupting lectures for over a million students in the run up to the Christmas break.
Other forms of industrial action will be launched including not covering for absent colleagues and refusing to reschedule lectures lost to strike action.
Those going on strike include lecturers, student support services staff, admissions tutors, librarians, technicians and administrators.
University leaders say they will try to lessen the impact of the action andinsist they want to work with the union to reach an agreement.
But the UCU said staff had reached "breaking point" over a number of 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.
Many universities were also employing academic staff on "discredited" zerohours contracts, said the union.
The General Secretary of the UCU, Jo Grady, said:
Carol Costello, spokesman for the employers' side, said that the UCU was insisting that employers should pay the full cost of an increase in pension contributions and had not been prepared to compromise:
Costello maintained that university employers were committed to ensuring staff had access to one of the best pension schemes in the country.
'Universities were working hard to ensure that students do not miss out or are disadvantaged by the strikes', she added.
University leaders have written to the union outlining their commitment to delivering long-term reform of the USS.
The strikes will take place on five days this week, and again for three days from 2 December.