Up to 78 biomedical scientists were still locked out at Northampton general hospital as Socialist Worker went to press.
Workers in the Unite union had refused to sign new contracts involving worse terms and conditions.
A meeting with the Acas conciliation service last Wednesday failed to resolved the dispute.
Another meeting is planned on Thursday of this week.
Management attempts to run the services with agency workers put patients at risk.
Unite sees the dispute as of national importance. Workers have been strengthened by Unite’s decision to pay all locked out workers full pay.
About 50 people were on the main picket line on Monday of this week.